0.8.1 release version

added clean import scope Scope.new()

.gitignore

@@ -14,3 +14,4 @@ xcuserdata
 .gigaide
 /kotlin-js-store/yarn.lock
 /test.lyng
+/sample_texts/1.txt.gz

README.md

@@ -9,6 +9,10 @@ class Point(x,y) {
    fun dist() { sqrt(x*x + y*y) } 
 }
 Point(3,4).dist() //< 5
+
+fun swapEnds(first, args..., last, f) {
+    f( last, ...args, first)
+} 
 ```
 
 - extremely simple Kotlin integration on any platform
@@ -31,26 +35,56 @@ and it is multithreaded on platforms supporting it (automatically, no code chang
 
 ## Integration in Kotlin multiplatform
 
-### Add library
+### Add dependency to your project
 
-TBD
+```kotlin
+// update to current please:
+val lyngVersion = "0.6.1-SNAPSHOT"
+
+repositories {
+    // ...
+    maven("https://gitea.sergeych.net/api/packages/SergeychWorks/maven")
+}
+```
+
+And add dependency to the proper place in your project, it could look like:
+
+```kotlin
+comminMain by getting {
+    dependencies {
+        // ...
+        implementation("net.sergeych:lynglib:$lyngVersion")
+    }
+}
+```
+
+Now you can import lyng and use it:
 
 ### Execute script:
 
 ```kotlin
-assertEquals("hello, world", eval(""" 
-    "hello, " + "world" 
-    """).toString())
+import net.sergeyh.lyng.*
+
+// we need a coroutine to start, as Lyng
+// is a coroutine based language, async topdown
+runBlocking {
+    assert(5 == eval(""" 3*3 - 4 """).toInt())
+    eval(""" println("Hello, Lyng!") """)
+}
 ```
 
 ### Exchanging information
 
-Script is executed over some `Context`. Create instance of the context,
-add your specific vars and functions to it, an call over it:
+Script is executed over some `Scope`. Create instance,
+add your specific vars and functions to it, and call:
 
 ```kotlin
+
+import com.sun.source.tree.Scope
+import new.sergeych.lyng.*
+
 // simple function
-val context = Context().apply {
+val scope = Scope().apply {
     addFn("addArgs") {
         var sum = 0.0
         for (a in args) sum += a.toDouble()
@@ -67,9 +101,9 @@ val context = Context().apply {
     }
 }
 // adding constant:
-context.eval("addArgs(1,2,3)") // <- 6
+scope.eval("addArgs(1,2,3)") // <- 6
 ```
-Note that the context stores all changes in it so you can make calls on a single context to preserve state between calls.
+Note that the scope stores all changes in it so you can make calls on a single scope to preserve state between calls.
 
 ## Why? 
 
@@ -83,22 +117,51 @@ Designed to add scripting to kotlin multiplatform application in easy and effici
 
 # Language 
 
-- dynamic 
-- async
-- multithreaded (coroutines could be dispatched using threads on appropriate platforms, automatically)
+- Javascript, WasmJS, native, JVM, android - batteries included.
+- dynamic types in most elegant and concise way
+- async, 100% coroutines, supports multiple cores where platofrm supports thread
+- good for functional an object-oriented style
 
-## By-stage
+# Language Roadmap
 
-Here are plans to develop it:
+## v1.0.0
 
-### First stage
+Planned autumn 2025. Complete dynamic language with sufficient standard library:
 
-Interpreted, precompiled into threaded code, actually. Dynamic types.
+Ready features:
 
-### Second stage
+- [x] Language platform and independent command-line launcher
+- [x] Integral types and user classes, variables and constants, functions
+- [x] lambdas and closures, coroutines for all callables
+- [x] while-else, do-while-else, for-else loops with break-continue returning values and labels support
+- [x] ranges, lists, strings, interfaces: Iterable, Iterator, Collection, Array
+- [x] when(value), if-then-else
+- [x] exception handling: throw, try-catch-finally, exception classes.
+- [x] multiplatform maven publication
+- [x] documentation for the current state
 
-Will add:
+Under way: 
 
-- optimizations
-- p-code serialization
-- static typing
+- [ ] maps, sets and sequences (flows?)
+- [ ] regular exceptions
+- [ ] modules
+- [ ] string interpolation and more string tools
+- [ ] multiple inheritance for user classes
+- [ ] launch, deferred, coroutineScope, mutex, etc.
+- [ ] site with integrated interpreter to give a try
+- [ ] kotlin part public API good docs, integration focused
+- [ ] better stack reporting
+
+## v1.1+
+
+Planned features.
+
+- [ ] type specifications
+- [ ] source docs and maybe lyng.md to a standard
+- [ ] moacro-style kotlin integration or something else to simplify it
+
+Further
+
+- [ ] client with GUI support based on compose multiplatform somehow
+- [ ] notebook - style workbooks with graphs, formulaes, etc.
+- [ ] language server or compose-based lyng-aware editor

bin/local_jrelease

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+set -e
+
+root=./lyng/build/install/lyng-jvm/
+
+./gradlew :lyng:installJvmDist
+#strip $file
+#upx   $file
+rm -rf ~/bin/jlyng-jvm || true
+rm ~/bin/jlyng 2>/dev/null || true
+mkdir -p ~/bin/jlyng-jvm
+cp -R $root ~/bin/jlyng-jvm
+ln -s ~/bin/jlyng-jvm/lyng-jvm/bin/lyng ~/bin/jlyng

bin/lyng_test

@@ -0,0 +1,3 @@
+#!/usr/bin/env lyng
+
+println("Hello from lyng!")

docs/Buffer.md

@@ -0,0 +1,121 @@
+# Binary `Buffer`
+
+Buffers are effective unsigned byte arrays of fixed size. Buffers content is mutable,
+unlike its size. Buffers are comparable and implement [Array], thus [Collection] and [Iterable]. Buffer iterators return
+its contents as unsigned bytes converted to `Int`
+
+Buffers needs to be imported with `import lyng.buffer`:
+
+    import lyng.buffer
+
+    assertEquals(5, Buffer("Hello").size)
+    >>> void
+
+Buffer is _immutable_, there is a `MutableBuffer` with same interface but mutable.
+
+## Constructing
+
+There are a lo of ways to construct a buffer:
+
+    import lyng.buffer
+    
+    // from string using utf8 encoding:
+    assertEquals( 5, Buffer("hello").size )
+
+    // from bytes, e.g. integers in range 0..255
+    assertEquals( 255, Buffer(1,2,3,255).last() )
+
+    // from whatever iterable that produces bytes, e.g.
+    // integers in 0..255 range:
+    assertEquals( 129, Buffer([1,2,129]).last() )
+
+    // Empty buffer of fixed size:
+    assertEquals(100, Buffer(100).size)
+    assertEquals(0, Buffer(100)[0])
+
+    // Note that you can use list iteral to create buffer with 1 byte:
+    assertEquals(1, Buffer([100]).size)
+    assertEquals(100, Buffer([100])[0])
+
+    >>> void
+
+## Accessing and modifying
+
+Buffer implement [Array] and therefore can be accessed, and `MutableBuffers` also modified:
+
+    import lyng.buffer
+    val b1 = Buffer( 1, 2, 3)
+    assertEquals( 2, b1[1] )
+
+    val b2 = b1.toMutable()
+    assertEquals( 2, b1[1] )
+    b2[1]++
+    b2[0] = 100
+    assertEquals( Buffer(100, 3, 3), b2)
+
+    // b2 is a mutable copy so b1 has not been changed:
+    assertEquals( Buffer(1, 2, 3), b1)
+
+    >>> void
+
+Buffer provides concatenation with another Buffer:
+
+    import lyng.buffer
+    val b = Buffer(101, 102)
+    assertEquals( Buffer(101, 102, 1, 2), b + [1,2])
+    >>> void
+
+Please note that indexed bytes are _readonly projection_, e.g. you can't modify these with
+
+## Comparing
+
+Buffers are comparable with other buffers (and notice there are _mutable_ buffers, bu default buffers ar _immutable_):
+
+    import lyng.buffer
+    val b1 = Buffer(1, 2, 3)
+    val b2 = Buffer(1, 2, 3)
+    val b3 = MutableBuffer(b2)
+    
+    b3[0] = 101
+
+    assert( b3 > b1 )
+    assert( b2 == b1 )
+    // longer string with same prefix is considered bigger:
+    assert( b2 + "!".characters() > b1 )
+    // note that characters() provide Iterable of characters that 
+    // can be concatenated to Buffer
+
+    >>> void
+
+## Slicing
+
+As with [List], it is possible to use ranges as indexes to slice a Buffer:
+
+    import lyng.buffer
+
+    val a = Buffer( 100, 101, 102, 103, 104, 105 )
+    assertEquals( a[ 0..1 ], Buffer(100, 101) )
+    assertEquals( a[ 0 ..< 2 ], Buffer(100, 101) )
+    assertEquals( a[  ..< 2 ], Buffer(100, 101) )
+    assertEquals( a[  4.. ], Buffer(104, 105) )
+    assertEquals( a[  2..3 ], Buffer(102, 103) )
+
+    >>> void
+
+## Members
+
+| name          | meaning                            | type          |
+|---------------|------------------------------------|---------------|
+| `size`        | size                               | Int           |
+| `decodeUtf8`  | decodee to String using UTF8 rules | Any           |
+| `+`           | buffer concatenation               | Any           |
+| `toMutable()` | create a mutable copy              | MutableBuffer |
+
+(1)
+: optimized implementation that override `Iterable` one
+
+Also, it inherits methods from [Iterable] and [Array].
+
+
+[Range]: Range.md
+[Iterable]: Iterable.md

docs/Collection.md

@@ -0,0 +1,13 @@
+# Collection
+
+Is a [Iterable] with known `size`, a finite [Iterable]:
+
+    class Collection : Iterable {
+        val size
+    }
+
+See [List], [Set] and [Iterable]
+
+[Iterable]: Iterable.md
+[List]: List.md
+[Set]: Set.md

docs/Iterable.md

@@ -1,13 +1,17 @@
 # Iterable interface
 
-The inteface which requires iterator to be implemented:
+Iterable is a class that provides function that creates _the iterator_:
 
-    fun iterator(): Iterator
+    class Iterable {
+        abstract fun iterator()
+    }
+
+Note that each call of `iterator()` must provide an independent iterator.
 
 Iterator itself is a simple interface that should provide only to method:
 
-    interface Iterable {
-        fun hasNext(): Bool
+    class Iterator {
+        abstract fun hasNext(): Bool
         fun next(): Obj
     }
 
@@ -15,19 +19,41 @@ Just remember at this stage typed declarations are not yet supported.
 
 Having `Iterable` in base classes allows to use it in for loop. Also, each `Iterable` has some utility functions available:
 
+## Instance methods
+
+| fun/method      | description                                                                     |
+|-----------------|---------------------------------------------------------------------------------|
+| toList()        | create a list from iterable                                                     |
+| toSet()         | create a set from iterable                                                      |
+| contains(i)     | check that iterable contains `i`                                                |
+| `i in iterator` | same as `contains(i)`                                                           |
+| isEmpty()       | check iterable is empty                                                         |
+| forEach(f)      | call f for each element                                                         |
+| toMap()         | create a map from list of key-value pairs (arrays of 2 items or like)           |
+| map(f)          | create a list of values returned by `f` called for each element of the iterable |
+| indexOf(i)      | return index if the first encounter of i or a negative value if not found       |
+| associateBy(kf) | create a map where keys are returned by kf that will be called for each element |
+
+
+    fun Iterable.toList(): List
+    fun Iterable.toSet(): Set
+    fun Iterable.indexOf(element): Int
+    fun Iterable.contains(element): Bool
+    fun Iterable.isEmpty(element): Bool
+    fun Iterable.forEach(block: (Any?)->Void ): Void
+    fun Iterable.map(block: (Any?)->Void ): List
+    fun Iterable.associateBy( keyMaker: (Any?)->Any): Map
+    
+
 ## Abstract methods
 
     fun iterator(): Iterator
 
-## Instance methods
-
-### toList()
-
 Creates a list by iterating to the end. So, the Iterator should be finite to be used with it.
 
 ## Included in interfaces:
 
-- Collection, Array, [List]
+- [Collection], Array, [List]
 
 ## Implemented in classes:
 

docs/List.md

@@ -20,11 +20,11 @@ indexing is zero-based, as in C/C++/Java/Kotlin, etc.
     list[1]
     >>> 20
 
-Using negative indexes has a special meaning: _offset from the end of the list_:
+There is a shortcut for the last:
 
     val list = [10, 20, 30]
-    list[-1]
-    >>> 30
+    [list.last, list.lastIndex]
+    >>> [30, 2]
 
 __Important__ negative indexes works wherever indexes are used, e.g. in insertion and removal methods too.
 
@@ -38,7 +38,8 @@ You can concatenate lists or iterable objects:
 
 ## Appending
 
-To append to lists, use `+=` with elements, lists and any [Iterable] instances, but beware it will concatenate [Iterable] objects instead of appending them. To append [Iterable] instance itself, use `list.add`:
+To append to lists, use `+=` with elements, lists and any [Iterable] instances, but beware it will
+concatenate [Iterable] objects instead of appending them. To append [Iterable] instance itself, use `list.add`:
 
     var list = [1, 2]
     val other = [3, 4]
@@ -57,7 +58,28 @@ To append to lists, use `+=` with elements, lists and any [Iterable] instances,
 
     >>> void
 
+## Removing elements
 
+List is mutable, so it is possible to remove its contents. To remove a single element
+by index use:
+
+    assertEquals( [1,2,3].removeAt(1), [1,3] )
+    assertEquals( [1,2,3].removeAt(0), [2,3] )
+    assertEquals( [1,2,3].removeLast(), [1,2] )
+    >>> void
+
+There is a way to remove a range (see [Range] for more on ranges):
+
+    assertEquals( [1, 4], [1,2,3,4].removeRange(1..2))
+    assertEquals( [1, 4], [1,2,3,4].removeRange(1..<3))
+    >>> void
+
+Open end ranges remove head and tail elements:
+
+    assertEquals( [3, 4, 5], [1,2,3,4,5].removeRange(..1))
+    assertEquals( [3, 4, 5], [1,2,3,4,5].removeRange(..<2))
+    assertEquals( [1, 2], [1,2,3,4,5].removeRange( (2..) ))
+    >>> void
 
 ## Comparisons
 
@@ -73,18 +95,43 @@ To append to lists, use `+=` with elements, lists and any [Iterable] instances,
 ## Members
 
 | name                          | meaning                               | type        |
-|-----------------------------------|-------------------------------------|----------|
+|-------------------------------|---------------------------------------|-------------|
 | `size`                        | current size                          | Int         |
 | `add(elements...)`            | add one or more elements to the end   | Any         |
-| `addAt(index,elements...)`        | insert elements at position         | Int, Any |
+| `insertAt(index,elements...)` | insert elements at position           | Int, Any    |
 | `removeAt(index)`             | remove element at position            | Int         |
-| `removeRangeInclusive(start,end)` | remove range, inclusive (1)         | Int, Int |
-|                                   |                                     |          |
+| `remove(from,toNonInclusive)` | remove range from (incl) to (nonincl) | Int, Int    |
+| `remove(Range)`               | remove range                          | Range       |
+| `removeLast()`                | remove last element                   |             |
+| `removeLast(n)`               | remove n last elements                | Int         |
+| `contains(element)`           | check the element is in the list (1)  |             |
+| `[index]`                     | get or set element at index           | Int         |
+| `[Range]`                     | get slice of the array (copy)         | Range       |
+| `+=`                          | append element(s)                     | List or Obj |
 
 (1)
-: end-inclisiveness allows to use negative indexes to, for exampe, remove several last elements, like `list.removeRangeInclusive(-2, -1)` will remove two last elements.
+: optimized implementation that override `Array` one
+
+(2)
+: `+=` append either a single element, or all elements if the List or other Iterable
+instance is appended. If you want to append an Iterable object itself, use `add` instead.
+
+It inherits from [Iterable] too.
+
+## Member inherited from Array
+
+| name             | meaning                        | type  |
+|------------------|--------------------------------|-------|
+| `last`           | last element (throws if empty) |       |
+| `lastOrNull`     | last element or null           |       |
+| `lastIndex`      |                                | Int   |
+| `indices`        | range of indexes               | Range |
+| `contains(item)` | test that item is in the list  |       |
+
+(1)
+: end-inclisiveness allows to use negative indexes to, for exampe, remove several last elements, like
+`list.removeRangeInclusive(-2, -1)` will remove two last elements.
 
 
-# Notes
-
-Could be rewritten using array as a class but List as the interface
+[Range]: Range.md
+[Iterable]: Iterable.md

docs/Map.md

@@ -0,0 +1,113 @@
+# Map
+
+Map is a mutable collection of key-value pars, where keys are unique. Maps could be created with
+constructor or `.toMap` methods. When constructing from a list, each list item must be a [Collection] with exactly 2 elements, for example, a [List].
+
+Important thing is that maps can't contain `null`: it is used to return from missing elements.
+
+Constructed map instance is of class `Map` and implements `Collection` (and therefore `Iterable`)
+
+    val map = Map( "foo" => 1, "bar" => "buzz" )
+    assert(map is Map)
+    assert(map.size == 2)
+    assert(map is Iterable)
+    >>> void
+
+Notice usage of the `=>` operator that creates `MapEntry`, which implements also [Collection] of
+two items, first, at index zero, is a key, second, at index 1, is the value. You can use lists too.
+Map keys could be any objects (hashable, e.g. with reasonable hashCode, most of standard types are). You can access elements with indexing operator:
+
+    val map = Map( ["foo", 1], ["bar", "buzz"], [42, "answer"] )
+    assert( map["bar"] == "buzz")
+    assert( map[42] == "answer" )
+    assertEquals( null, map["nonexisting"])
+    assert( map.getOrNull(101) == null )
+    assert( map.getOrPut(911) { "nine-eleven" } == "nine-eleven" )
+    // now 91 entry is set:
+    assert( map[911] == "nine-eleven" )
+    map["foo"] = -1
+    assert( map["foo"] == -1)
+    >>> void
+
+To remove item from the collection. use `remove`. It returns last removed item or null. Be careful if you 
+hold nulls in the map - this is not a recommended practice when using `remove` returned value. `clear()` 
+removes all.
+
+    val map = Map( "foo" => 1, "bar" => "buzz", [42, "answer"] )
+    assertEquals( 1, map.remove("foo") )
+    assert( map.getOrNull("foo") == null)
+    assert( map.size == 2 )
+    map.clear()
+    assert( map.size == 0 )
+    >>> void
+
+Map implements [contains] method that checks _the presence of the key_ in the map:
+
+    val map = Map( ["foo", 1], ["bar", "buzz"], [42, "answer"] )
+    assert( "foo" in map )
+    assert( "answer" !in map )
+    >>> void
+
+To iterate maps it is convenient to use `keys` method that returns [Set] of keys (keys are unique:
+
+    val map = Map( ["foo", 1], ["bar", "buzz"], [42, "answer"] )
+    for( k in map.keys ) println(map[k])
+    >>> 1
+    >>> buzz
+    >>> answer
+    >>> void
+
+Or iterate its key-value pairs that are instances of [MapEntry] class:
+
+    val map = Map( ["foo", 1], ["bar", "buzz"], [42, "answer"] )
+    for( entry in map ) {
+        println("map[%s] = %s"(entry.key, entry.value))
+    }
+    void
+    >>> map[foo] = 1
+    >>> map[bar] = buzz
+    >>> map[42] = answer
+    >>> void
+
+There is a shortcut to use `MapEntry` to create maps: operator `=>` which creates `MapEntry`:
+
+    val entry = "answer" => 42
+    assert( entry is MapEntry )
+    >>> void
+
+And you can use it to construct maps:
+
+    val map = Map( "foo" => 1, "bar" => 22)
+    assertEquals(1, map["foo"])
+    assertEquals(22, map["bar"])
+    >>> void
+
+Or use `.toMap` on anything that implements [Iterable] and which elements implements [Array] with 2 elements size, for example, `MapEntry`:
+
+    val map = ["foo" => 1, "bar" => 22].toMap()
+    assert( map is Map )
+    assertEquals(1, map["foo"])
+    assertEquals(22, map["bar"])
+    >>> void
+
+
+It is possible also to get values as [List] (values are not unique):
+
+    val map = Map( ["foo", 1], ["bar", "buzz"], [42, "answer"] )
+    assertEquals(map.values, [1, "buzz", "answer"] )
+    >>> void
+
+Map could be tested to be equal: when all it key-value pairs are equal, the map
+is equal.
+
+    val m1 = Map(["foo", 1])
+    val m2 = Map(["foo", 1])
+    val m3 = Map(["foo", 2])
+    assert( m1 == m2 )
+    // but the references are different:
+    assert( m1 !== m2 )
+    // different maps:
+    assert( m1 != m3 )
+    >>> void
+
+[Collection](Collection.md)

docs/OOP.md

@@ -147,7 +147,7 @@ In many cases it is necessary to implement custom comparison and `toString`, sti
 each class is provided with default implementations:
 
 - default toString outputs class name and its _public_ fields.
-- default comparison compares compares all public fields in order of appearance.
+- default comparison compares all fields in order of appearance.
 
 For example, for our class Point:
 
@@ -160,6 +160,81 @@ For example, for our class Point:
     Point(1,1+1)
     >>> Point(x=1,y=2)
 
+## Statics: class fields and class methods
+
+You can mark a field or a method as static. This is borrowed from Java as more plain version of a kotlin's companion object or Scala's object. Static field and functions is one for a class, not for an instance. From inside the class, e.g. from the class method, it is a regular var. From outside, it is accessible as `ClassName.field` or method:
+
+
+    class Value(x) {
+        static var foo = Value("foo")
+
+        static fun exclamation() {
+            // here foo is a regular var:
+            foo.x + "!"
+        }
+    }
+    assertEquals( Value.foo.x, "foo" )
+    assertEquals( "foo!", Value.exclamation() )
+
+    // we can access foo from outside like this:
+    Value.foo = Value("bar")
+    assertEquals( "bar!", Value.exclamation() )
+    >>> void
+
+As usual, private statics are not accessible from the outside:
+
+    class Test {
+        // private, inacessible from outside protected data:
+        private static var data = null
+
+        // the interface to access and change it:
+        static fun getData() { data }
+        static fun setData(value) { data = value }
+    }
+
+    // no direct access:
+    assertThrows { Test.data }
+
+    // accessible with the interface:
+    assertEquals( null, Test.getData() )
+    Test.setData("fubar")
+    assertEquals("fubar", Test.getData() )
+    >>> void
+
+# Extending classes
+
+It sometimes happen that the class is missing some particular functionality that can be _added to it_ without rewriting its inner logic and using its private state. In this case _extension methods_ could be used, for example. we want to create an extension method
+that would test if some object of unknown type contains something that can be interpreted
+as an integer. In this case we _extend_ class `Object`, as it is the parent class for any instance of any type:
+
+        fun Object.isInteger() {
+            when(this) {
+                // already Int?
+                is Int -> true
+
+                // real, but with no declimal part?
+                is Real -> toInt() == this
+
+                // string with int or real reuusig code above
+                is String -> toReal().isInteger()
+                
+                // otherwise, no:
+                else -> false
+            }
+        }
+
+        // Let's test:        
+        assert( 12.isInteger() == true )
+        assert( 12.1.isInteger() == false )
+        assert( "5".isInteger() )
+        assert( ! "5.2".isInteger() )
+        >>> void
+
+__Important note__ as for version 0.6.9, extensions are in __global scope__. It means, that once applied to a global type (Int in our sample), they will be available for _all_ contexts, even new created, 
+as they are modifying the type, not the context.
+
+Beware of it. We might need to reconsider it later.
+
 # Theory
 
 ## Basic principles:
@@ -216,11 +291,10 @@ Note `Real` class: it is global variable for Real class; there are such class in
     assert('$'::class == Char)
     >>> void
 
-More complex is singleton classes, because you don't need to compare their class
-instances and generally don't need them at all, these are normally just Obj:
+Singleton classes also have class:
 
     null::class
-    >>> Obj
+    >>> Null
 
 At this time, `Obj` can't be accessed as a class.
 

docs/Real.md

@@ -16,9 +16,9 @@ you can use it's class to ensure type:
 ## Member functions
 
 | name            | meaning                                                     | type |
-|-----------------|------------------------------------|------|
+|-----------------|-------------------------------------------------------------|------|
 | `.roundToInt()` | round to nearest int like round(x)                          | Int  |
-|                 |                                    |      |
+| `.toInt()`      | convert integer part of real to `Int` dropping decimal part | Int  |
 |                 |                                                             |      |
 |                 |                                                             |      |
 |                 |                                                             |      |

docs/Set.md

@@ -0,0 +1,94 @@
+# List built-in class
+
+Mutable set of any objects: a group of different objects, no repetitions.
+Sets are not ordered, order of appearance does not matter.
+
+    val set = Set(1,2,3, "foo")
+    assert( 1 in set )
+    assert( "foo" in set)
+    assert( "bar" !in set)
+    >>> void
+
+## Set is collection and therefore [Iterable]:
+
+    assert( Set(1,2) is Set)
+    assert( Set(1,2) is Iterable)
+    assert( Set(1,2) is Collection)
+    >>> void
+
+So it supports all methods from [Iterable]; set is not, though, an [Array] and has
+no indexing. Use [set.toList] as needed.
+
+## Set operations
+
+    // Union
+    assertEquals( Set(1,2,3,4), Set(3, 1) + Set(2, 4))
+
+    // intersection
+    assertEquals( Set(1,4), Set(3, 1, 4).intersect(Set(2, 4, 1)) )
+    // or simple
+    assertEquals( Set(1,4), Set(3, 1, 4) * Set(2, 4, 1) )
+
+    // To find collection elements not present in another collection, use the 
+    // subtract() or `-`:
+    assertEquals( Set( 1, 2), Set(1, 2, 4, 3) - Set(3, 4))
+
+    >>> void
+
+## Adding elements
+
+    var s = Set()
+    s += 1
+    assertEquals( Set(1), s)
+    
+    s += [3, 3, 4]
+    assertEquals( Set(3, 4, 1), s)
+    >>> void
+
+## Removing elements
+
+List is mutable, so it is possible to remove its contents. To remove a single element
+by index use:
+
+    var s = Set(1,2,3)
+    s.remove(2)
+    assertEquals( s, Set(1,3) )
+
+    s = Set(1,2,3)
+    s.remove(2,1)
+    assertEquals( s, Set(3) )
+    >>> void
+
+Note that `remove` returns true if at least one element was actually removed and false
+if the set has not been changed.
+
+## Comparisons and inclusion
+
+Sets are only equal when contains exactly same elements, order, as was said, is not significant:
+
+    assert( Set(1, 2) == Set(2, 1) )
+    assert( Set(1, 2, 2) == Set(2, 1) )
+    assert( Set(1, 3) != Set(2, 1) )
+    assert( 1 in Set(5,1))
+    assert( 10 !in Set(5,1))
+    >>> void
+
+## Members
+
+| name                | meaning                              | type  |
+|---------------------|--------------------------------------|-------|
+| `size`              | current size                         | Int   |
+| `+=`                | add one or more elements             | Any   |
+| `+`, `union`         | union sets                           | Any   |
+| `-`, `subtract`     | subtract sets                        | Any   |
+| `*`, `intersect`    | subtract sets                        | Any   |
+| `remove(items...)`  | remove one or more items             | Range |
+| `contains(element)` | check the element is in the list (1) |       |
+
+(1)
+: optimized implementation that override `Iterable` one
+
+Also, it inherits methods from [Iterable].
+
+
+[Range]: Range.md

docs/advanced_topics.md

@@ -87,3 +87,27 @@ Lambda functions remember their scopes, so it will work the same as previous:
     println(c)
     >> 1
     >> void
+
+# Elements of functional programming
+
+With ellipsis and splats you can create partial functions, manipulate
+arguments list in almost arbitrary ways. For example:
+
+    // Swap first and last arguments for call
+
+    fun swap_args(first, others..., last, f) { 
+        f(last, ...others, first) 
+    }
+
+    fun glue(args...) {
+        var result = ""
+        for( a in args ) result += a
+    }
+
+    assertEquals( 
+        "4231", 
+        swap_args( 1, 2, 3, 4, glue)
+    )
+    >>> void
+
+,

docs/exceptions_handling.md

@@ -81,6 +81,22 @@ to catch all exceptions to, then you can write it even shorter:
 You can even check the type of the `it` and create more convenient and sophisticated processing logic. Such approach is
 used, for example, in Scala.
 
+## finally block
+
+If `finally` block present, it will be executed after body (until first exception)
+and catch block, if any will match. finally statement is executed even if the
+exception will be thrown and not caught locally. It does not alter try/catch block result:
+
+    try {
+    }
+    finally {
+        println("called finally")
+    }
+    >>> called finally
+    >>> void
+
+- and yes, there could be try-finally block, no catching, but perform some guaranteed cleanup.
+
 # Conveying data with exceptions
 
 The simplest way is to provide exception string and `Exception` class:
@@ -115,7 +131,7 @@ _this functionality is not yet released_
 | class                      | notes                                                 |
 |----------------------------|-------------------------------------------------------|
 | Exception                  | root of al throwable objects                          |
-| NullPointerException       |                                                       |
+| NullReferenceException       |                                                       |
 | AssertionFailedException   |                                                       | 
 | ClassCastException         |                                                       |
 | IndexOutOfBoundsException  |                                                       |

docs/samples/helloworld.lyng

@@ -1,2 +1,3 @@
+#!/bin/env jlyng
 
 println("Hello, world!");

docs/time.md

@@ -0,0 +1,215 @@
+# Lyng time functions
+
+Lyng date and time support requires importing `lyng.time` packages. Lyng uses simple yet modern time object models:
+
+- `Instant` class for time stamps with platform-dependent resolution
+- `Duration` to represent amount of time not depending on the calendar, e.g. in absolute units (milliseconds, seconds,
+  hours, days)
+
+## Time instant: `Instant`
+
+Represent some moment of time not depending on the calendar (calendar for example may b e changed, daylight saving time
+can be for example introduced or dropped). It is similar to `TIMESTAMP` in SQL or `Instant` in Kotlin. Some moment of
+time; not the calendar date.
+
+Instant is comparable to other Instant. Subtracting instants produce `Duration`, period in time that is not dependent on
+the calendar, e.g. absolute time period.
+
+It is possible to add or subtract `Duration` to and from `Instant`, that gives another `Instant`.
+
+Instants are converted to and from `Real` number of seconds before or after Unix Epoch, 01.01.1970. Constructor with
+single number parameter constructs from such number of seconds,
+and any instance provide `.epochSeconds` member:
+
+    import lyng.time
+
+    // default constructor returns time now:
+    val t1 = Instant()
+    val t2 = Instant()
+    assert( t2 - t1 < 1.millisecond )
+    assert( t2.epochSeconds - t1.epochSeconds < 0.001 )
+    >>> void
+
+## Constructing
+
+    import lyng.time
+
+    // empty constructor gives current time instant using system clock:
+    val now = Instant()
+
+    // constructor with Instant instance makes a copy:
+    assertEquals( now, Instant(now) )
+
+    // constructing from a number is trated as seconds since unix epoch:
+    val copyOfNow = Instant( now.epochSeconds )
+
+    // note that instant resolution is higher that Real can hold
+    // so reconstructed from real slightly differs:
+    assert( abs( (copyOfNow - now).milliseconds ) < 0.01 )
+    >>> void
+
+The resolution of system clock could be more precise and double precision real number of `Real`, keep it in mind.
+
+## Comparing and calculating periods
+
+    import lyng.time
+    
+    val now = Instant()
+    
+    // you cam add or subtract periods, and compare
+    assert( now - 5.minutes < now )
+    val oneHourAgo = now - 1.hour
+    assertEquals( now, oneHourAgo + 1.hour)
+
+    >>> void
+
+## Getting the max precision
+
+Normally, subtracting instants gives precision to microseconds, which is well inside the jitter
+the language VM adds. Still `Instant()` or `Instant.now()` capture most precise system timer at hand and provide inner
+value of 12 bytes, up to nanoseconds (hopefully). To access it use:
+
+    import lyng.time
+
+    // capture time
+    val now = Instant.now()
+
+    // this is Int value, number of whole epoch 
+    // milliseconds to the moment, it fits 8 bytes Int well
+    val seconds = now.epochWholeSeconds
+    assert(seconds is Int)
+
+    // and this is Int value of nanoseconds _since_ the epochMillis,
+    // it effectively add 4 more mytes int:
+    val nanos = now.nanosecondsOfSecond
+    assert(nanos is Int)
+    assert( nanos in 0..999_999_999 )
+
+    // we can construct epochSeconds from these parts:
+    assertEquals( now.epochSeconds, nanos * 1e-9 + seconds )
+    >>> void
+
+## Truncating to more realistic precision
+
+Full precision Instant is way too long and impractical to store, especially when serializing,
+so it is possible to truncate it to milliseconds, microseconds or seconds:
+
+    import lyng.time
+    import lyng.serialization
+
+    // max supported size (now microseconds for serialized value):
+    // note that encoding return _bit array_ and this is a _bit size_:
+    val s0 = Lynon.encode(Instant.now()).size
+
+    // shorter: milliseconds only
+    val s1 = Lynon.encode(Instant.now().truncateToMillisecond()).size
+
+    // truncated to seconds, good for file mtime, etc:
+    val s2 = Lynon.encode(Instant.now().truncateToSecond()).size 
+    assert( s1 < s0 )
+    assert( s2 < s1 )
+    >>> void
+
+## Formatting instants
+
+You can freely use `Instant` in string formatting. It supports usual sprintf-style formats:
+
+        import lyng.time
+        val now = Instant()
+
+        // will be something like "now: 12:10:05"
+        val currentTimeOnly24 =  "now: %tT"(now)
+
+        // we can extract epoch second with formatting too,
+        // this was since early C time
+
+        // get epoch while seconds from formatting
+        val unixEpoch = "Now is %ts since unix epoch"(now)
+        
+        // and it is the same as now.epochSeconds, int part:
+        assertEquals( unixEpoch, "Now is %d since unix epoch"(now.epochSeconds.toInt()) )
+        >>> void
+
+See
+the [complete list of available formats](https://github.com/sergeych/mp_stools?tab=readme-ov-file#datetime-formatting)
+and the [formatting reference](https://github.com/sergeych/mp_stools?tab=readme-ov-file#printf--sprintf): it all works
+in Lyng as `"format"(args...)`!
+
+## Instant members
+
+| member                         | description                                             |
+|--------------------------------|---------------------------------------------------------|
+| epochSeconds: Real             | positive or negative offset in seconds since Unix epoch |
+| epochWholeSeconds: Int         | same, but in _whole seconds_. Slightly faster           |
+| nanosecondsOfSecond: Int       | offset from epochWholeSeconds in nanos (1)              |
+| isDistantFuture: Bool          | true if it `Instant.distantFuture`                      |
+| isDistantPast: Bool            | true if it `Instant.distantPast`                        |
+| truncateToSecond: Intant       | create new instnce truncated to second                  |  
+| truncateToMillisecond: Instant | truncate new instance with to millisecond               |
+| truncateToMicrosecond: Instant | truncate new instance to microsecond                    |
+
+(1)
+: The value of nanoseconds is to be added to `epochWholeSeconds` to get exact time point. It is in 0..999_999_999 range.
+The precise time instant value therefore needs as for now 12 bytes integer; we might use bigint later (it is planned to
+be added)
+
+## Class members
+
+| member                         | description                                  |
+|--------------------------------|----------------------------------------------|
+| Instant.now()                  | create new instance with current system time |
+| Instant.distantPast: Instant   | most distant instant in past                 |
+| Instant.distantFuture: Instant | most distant instant in future               |
+
+# `Duraion` class
+
+Represent absolute time distance between two `Instant`.
+
+    import lyng.time
+    val t1 = Instant()
+
+    // yes we can delay to period, and it is not blocking. is suspends!
+    delay(1.millisecond)
+
+    val t2 = Instant()
+    // be suspend, so actual time may vary:
+    assert( t2 - t1 >= 1.millisecond)
+    assert( t2 - t1 < 100.millisecond)
+    >>> void
+
+Duration can be converted from numbers, like `5.minutes` and so on. Extensions are created for
+`Int` and `Real`, so for n as Real or Int it is possible to create durations::
+
+- `n.millisecond`, `n.milliseconds`
+- `n.second`, `n.seconds`
+- `n.minute`, `n.minutes`
+- `n.hour`, `n.hours`
+- `n.day`, `n.days`
+
+The bigger time units like months or years are calendar-dependent and can't be used with `Duration`.
+
+Each duration instance can be converted to number of any of these time units, as `Real` number, if `d` is a `Duration`
+instance:
+
+- `d.microseconds`
+- `d.milliseconds`
+- `d.seconds`
+- `d.minutes`
+- `d.hours`
+- `d.days`
+
+for example
+
+    import lyng.time
+    assertEquals( 60, 1.minute.seconds )
+    assertEquals( 10.milliseconds, 0.01.seconds )
+
+    >>> void
+
+# Utility functions
+
+## delay(duration: Duration)
+
+Suspends current coroutine for at least the specified duration.
+
+

docs/tutorial.md

@@ -14,7 +14,7 @@ __Other documents to read__ maybe after this one:
 - [Advanced topics](advanced_topics.md), [declaring arguments](declaring_arguments.md)
 - [OOP notes](OOP.md), [exception handling](exceptions_handling.md)
 - [math in Lyng](math.md)
-- Some class references: [List], [Real], [Range], [Iterable], [Iterator]
+- Some class references: [List], [Set], [Map], [Real], [Range], [Iterable], [Iterator], [time manipulation](time.md)
 - Some samples: [combinatorics](samples/combinatorics.lyng.md), national vars and loops: [сумма ряда](samples/сумма_ряда.lyng.md). More at [samples folder](samples)
 
 # Expressions
@@ -118,6 +118,109 @@ These operators return rvalue, unmodifiable.
 
 ## Assignment return r-value!
 
+Naturally, assignment returns its value:
+
+    var x
+    x = 11
+    >>> 11
+
+rvalue means you cant assign the result if the assignment
+
+    var x
+    assertThrows { (x = 11) = 5 }
+    void
+    >>> void
+
+This also prevents chain assignments so use parentheses:
+
+    var x
+    var y
+    x = (y = 1)
+    >>> 1
+
+## Nullability
+
+When the value is `null`, it might throws `NullReferenceException`, the name is somewhat a tradition. To avoid it
+one can check it against null or use _null coalescing_. The null coalescing means, if the operand (left) is null,
+the operation won't be performed and the result will be null. Here is the difference:
+
+    val ref = null
+    assertThrows {  ref.field }
+    assertThrows {  ref.method() }
+    assertThrows {  ref.array[1] }
+    assertThrows {  ref[1] }
+    assertThrows {  ref() }
+    
+    assert( ref?.field == null )
+    assert( ref?.method() == null )
+    assert( ref?.array?[1] == null )
+    assert( ref?[1] == null )
+    assert( ref?() == null )
+    >>> void
+
+There is also "elvis operator", null-coalesce infix operator '?:' that returns rvalue if lvalue is `null`:
+
+    null ?: "nothing"
+    >>> "nothing"
+
+## Utility functions
+
+The following functions simplify nullable values processing and
+allow to improve code look and readability. There are borrowed from Kotlin:
+
+### let 
+
+`value.let {}` passes to the block value as the single parameter (by default it is assigned to `it`) and return block's returned value. It is useful dealing with null or to
+get a snapshot of some externally varying value, or with `?.` to process nullable value in a safe manner:
+
+    // this state is changed from parallel processes
+    class GlobalState(nullableParam)
+    
+    val state = GlobalState(null)
+
+    fun sample() {
+        state.nullableParam?.let { "it's not null: "+it} ?: "it's null"
+    }
+    assertEquals(sample(), "it's null")
+    state.nullableParam = 5
+    assertEquals(sample(), "it's not null: 5")
+    >>> void
+
+This is the same as:
+
+    fun sample() {
+        val it = state.nullableParam
+        if( it != null )  "it's not null: "+it else "it's null"
+    }
+
+The important is that nullableParam got a local copy that can't be changed from any
+parallel thread/coroutine. Remember: Lyng _is __not__ a single-threaded language_.
+
+## Also
+
+Much like let, but it does not alter returned value:
+
+    assert( "test".also { println( it + "!") } == "test" )
+    >>> test!
+    >>> void
+
+While it is not altering return value, the source object could be changed:
+
+    class Point(x,y)
+    val p = Point(1,2).also { it.x++ }
+    assertEquals(p.x, 2)
+    >>> void
+
+## apply
+
+It works much like `also`, but is executed in the context of the source object:
+
+    class Point(x,y)
+    // see the difference: apply changes this to newly created Point:
+    val p = Point(1,2).apply { x++; y++ }
+    assertEquals(p, Point(2,3))
+    >>> void
+
 ## Math
 
 It is rather simple, like everywhere else:
@@ -427,7 +530,8 @@ The simplest way to concatenate lists is using `+` and `+=`:
     list += [2, 1]      
     // or you can append a single element:
     list += "end"
-    assert( list == [1, 2, 2, 1, "end"])
+    assertEquals( list, [1, 2, 2, 1, "end"])
+    void
     >>> void
 
 ***Important note***: the pitfall of using `+=` is that you can't append in [Iterable] instance as an object: it will always add all its contents. Use `list.add` to add a single iterable instance:
@@ -469,64 +573,101 @@ To add elements to the list:
     assert( x == [1, 2, 3, "the", "end"])
     >>> void
 
-Self-modifying concatenation by `+=` also works:
+Self-modifying concatenation by `+=` also works (also with single elements):
 
     val x = [1, 2]
     x += [3, 4]
-    assert( x == [1, 2, 3, 4])
+    x += 5
+    assert( x == [1, 2, 3, 4, 5])
     >>> void
 
-You can insert elements at any position using `addAt`:
+You can insert elements at any position using `insertAt`:
 
     val x = [1,2,3]
-    x.addAt(1, "foo", "bar")
+    x.insertAt(1, "foo", "bar")
     assert( x == [1, "foo", "bar", 2, 3])
     >>> void
 
 Using splat arguments can simplify inserting list in list:
 
     val x = [1, 2, 3]
-    x.addAt( 1, ...[0,100,0])
+    x.insertAt( 1, ...[0,100,0])
     x
     >>> [1, 0, 100, 0, 2, 3]
 
-Using negative indexes can insert elements as offset from the end, for example:
-
-    val x = [1,2,3]
-    x.addAt(-1, 10)
-    x
-    >>> [1, 2, 10, 3]
 
 Note that to add to the end you still need to use `add` or positive index of the after-last element:
 
     val x = [1,2,3]
-    x.addAt(3, 10)
+    x.insertAt(3, 10)
     x
     >>> [1, 2, 3, 10]
 
+but it is much simpler, and we recommend to use '+='
+
+    val x = [1,2,3]
+    x += 10
+    >>> [1, 2, 3, 10]
+
 ## Removing list items
 
     val x = [1, 2, 3, 4, 5]
     x.removeAt(2)
     assert( x == [1, 2, 4, 5])
     // or remove range (start inclusive, end exclusive):
-    x.removeRangeInclusive(1,2)    
+    x.removeRange(1..2)    
     assert( x == [1, 5])
     >>> void
 
-Again, you can use negative indexes. For example, removing last elements like:
+There is a shortcut to remove the last elements:
 
     val x = [1, 2, 3, 4, 5]
 
     // remove last:
-    x.removeAt(-1)
+    x.removeLast()
     assert( x == [1, 2, 3, 4])
     
     // remove 2 last:
-    x.removeRangeInclusive(-2,-1)
-    assert( x == [1, 2])
+    x.removeLast(2)
+    assertEquals( [1, 2], x)
     >>> void
 
+You can get ranges to extract a portion from a list:
+
+    val list = [1, 2, 3, 4, 5]
+    assertEquals( [1,2,3], list[..2])
+    assertEquals( [1,2,], list[..<2])
+    assertEquals( [4,5], list[3..])
+    assertEquals( [2,3], list[1..2])
+    assertEquals( [2,3], list[1..<3])
+    >>> void
+
+# Buffers
+
+[Buffer] is a special implementation of an [Array] of unsigned bytes, in the
+[separate file](Buffer.md).
+
+# Sets
+
+Set are unordered collection of unique elements, see [Set]. Sets are [Iterable] but have no indexing access.
+
+    assertEquals( Set(3, 2, 1), Set( 1, 2, 3))
+    assert( 5 !in Set(1, 2, 6) )
+    >>> void
+
+Please see [Set] for detailed description.
+
+# Maps
+
+Maps are unordered collection of key-value pairs, where keys are unique. See [Map] for details. Map also
+are [Iterable]:
+
+    val m = Map( "foo" => 77, "bar" => "buzz" )
+    assertEquals( m["foo"], 77 )
+    >>> void
+
+Please see [Map] reference for detailed description on using Maps.
+
 # Flow control operators
 
 ## if-then-else
@@ -552,6 +693,92 @@ Or, more neat:
     >>> just 3
     >>> void
 
+## When
+
+It is very much like the kotlin's:
+
+    fun type(x) {
+        when(x) {
+            in 'a'..'z', in 'A'..'Z' -> "letter"
+            in '0'..'9' -> "digit"
+            '$' -> "dollar"
+            "EUR" -> "crap"
+            in ['@', '#', '^'] -> "punctuation1"
+            in "*&.," -> "punctuation2"
+            else -> "unknown"
+        }
+    }
+    assertEquals("digit", type('3'))
+    assertEquals("dollar", type('$'))
+    assertEquals("crap", type("EUR"))
+    >>> void
+
+Notice, several conditions can be grouped with a comma.
+Also, you can check the type too:
+
+    fun type(x) {
+        when(x) {
+            "42", 42 -> "answer to the great question"
+            is Real, is Int -> "number"
+            is String -> {
+                for( d in x ) {
+                    if( d !in '0'..'9' ) 
+                        break "unknown"
+                }
+                else "number"
+            }
+        }
+    }
+    assertEquals("number", type(5))
+    assertEquals("number", type("153"))
+    assertEquals("number", type(π/2))
+    assertEquals("unknown", type("12%"))
+    assertEquals("answer to the great question", type(42))
+    assertEquals("answer to the great question", type("42"))
+    >>> void
+
+### supported when conditions:
+
+#### Contains: 
+
+You can thest that _when expression_ is _contained_, or not contained, in some object using `in container` and `!in container`. The container is any object that provides `contains` method, otherwise the runtime exception will be thrown.
+
+Typical builtin types that are containers (e.g. support `conain`):
+
+| class      | notes                                          |
+|------------|------------------------------------------------|
+| Collection | contains an element (1)                        |
+| Array      | faster maybe that Collection's                 |
+| List       | faster than Array's                            |
+| String     | character in string or substring in string (3) |
+| Range      | object is included in the range (2)            |
+
+(1)
+: Iterable is not the container as it can be infinite
+
+(2)
+: Depending on the inclusivity and open/closed range parameters. BE careful here: String range is allowed, but it is usually not what you expect of it:
+
+    assert( "more" in "a".."z") // string range ok
+    assert( 'x' !in "a".."z") // char in string range: probably error
+    assert( 'x' in 'a'..'z') // character range: ok
+    assert( "x" !in 'a'..'z') // string in character range: could be error
+    >>> void
+
+(3)
+: `String` also can provide array of characters directly with `str.characters()`, which is [Iterable] and [Array]. String itself is not iterable as otherwise it will interfere when adding strigns to lists (it will add _characters_ it it would be iterable).
+
+So we recommend not to mix characters and string ranges; use `ch in str` that works
+as expected:
+
+    "foo" in "foobar"
+    >>> true
+
+and also character inclusion:
+
+    'o' in "foobar"
+    >>> true
+
 ## while
 
 Regular pre-condition while loop, as expression, loop returns the last expression as everything else:
@@ -873,6 +1100,17 @@ and you can use ranges in for-loops:
 
 See [Ranges](Range.md) for detailed documentation on it.
 
+# Time routines
+
+These should be imported from [lyng.time](time.md). For example:
+
+    import lyng.time
+
+    val now = Instant()
+    val hourAgo = now - 1.hour
+
+See [more docs on time manipulation](time.md)
+
 # Comments
 
     // single line comment
@@ -923,15 +1161,56 @@ Are the same as in string literals with little difference:
 
 ## String details
 
-Strings are much like Kotlin ones:
+Strings are arrays of Unicode characters. It can be indexed, and indexing will
+return a valid Unicode character at position. No utf hassle:
 
-    "Hello".length
+    "Парашют"[5]
+    >>> 'ю'
+
+Its length is, of course, in characters:
+
+    "разум".length
     >>> 5
+
 And supports growing set of kotlin-borrowed operations, see below, for example:
 
     assertEquals("Hell", "Hello".dropLast(1))
     >>> void
 
+To format a string use sprintf-style modifiers like:
+
+    val a = "hello"
+    val b = 11
+    assertEquals( "hello:11", "%s:%d"(a, b) )
+    assertEquals( " hello:    11", "%6s:%6d"(a, b) )
+    assertEquals( "hello :11    ", "%-6s:%-6d"(a, b) )
+    >>> void
+
+List of format specifiers closely resembles C sprintf() one. See [format specifiers](https://github.com/sergeych/mp_stools?tab=readme-ov-file#sprintf-syntax-summary), this is doe using [mp_stools kotlin multiplatform library](https://github.com/sergeych/mp_stools). Currently supported Lyng types are `String`, `Int`, `Real`, `Bool`, the rest are displayed using their `toString()` representation.
+
+This list will be extended.
+
+To get the substring use:
+
+    assertEquals("pult", "catapult".takeLast(4))
+    assertEquals("cat", "catapult".take(3))
+    assertEquals("cat", "catapult".dropLast(5))
+    assertEquals("pult", "catapult".drop(4))
+    >>> void
+
+And to get a portion you can slice it with range as the index:
+
+    assertEquals( "tap", "catapult"[ 2 .. 4 ])
+    assertEquals( "tap", "catapult"[ 2 ..< 5 ])
+    >>> void
+
+Open-ended ranges could be used to get start and end too:
+
+    assertEquals( "cat", "catapult"[ ..< 3 ])
+    assertEquals( "cat", "catapult"[ .. 2 ])
+    assertEquals( "pult", "catapult"[ 4.. ])
+    >>> void
+
 ### String operations
 
 Concatenation is a `+`: `"hello " + name` works as expected. No confusion.
@@ -939,16 +1218,28 @@ Concatenation is a `+`: `"hello " + name` works as expected. No confusion.
 Typical set of String functions includes:
 
 | fun/prop          | description / notes                                        |
-|------------------|------------------------------------------------------------|
+|-------------------|------------------------------------------------------------|
 | lower()           | change case to unicode upper                               |
 | upper()           | change case to unicode lower                               |
 | startsWith(prefix) | true if starts with a prefix                               |
+| endsWith(prefix)  | true if ends with a prefix                                 |
 | take(n)           | get a new string from up to n first characters             |
 | takeLast(n)       | get a new string from up to n last characters              |
 | drop(n)           | get a new string dropping n first chars, or empty string   |
 | dropLast(n)       | get a new string dropping n last chars, or empty string    |
 | size              | size in characters like `length` because String is [Array] |
+| (args...)         | sprintf-like formatting, see [string formatting]           |
+| [index]           | character at index                                         | 
+| [Range]           | substring at range                                         |
+| s1 + s2           | concatenation                                              |
+| s1 += s2          | self-modifying concatenation                               |
+| toReal()          | attempts to parse string as a Real value                   |
+| toInt()           | parse string to Int value                                  |
+| characters()      | create [List] of characters (1)                            |
+| encodeUtf8()      | returns [Buffer] with characters encoded to utf8           |
 
+(1)
+: List is mutable therefore a new copy is created on each call.
 
 
 
@@ -983,5 +1274,8 @@ See [math functions](math.md). Other general purpose functions are:
 [Iterator]: Iterator.md
 [Real]: Real.md
 [Range]: Range.md
-
-
+[String]: String.md
+[string formatting]: https://github.com/sergeych/mp_stools?tab=readme-ov-file#sprintf-syntax-summary
+[Set]: Set.md
+[Map]: Map.md
+[Buffer]: Buffer.md

gradle/libs.versions.toml

@@ -8,6 +8,7 @@ kotlinx-coroutines = "1.10.1"
 mp_bintools = "0.1.12"
 firebaseCrashlyticsBuildtools = "3.0.3"
 okioVersion = "3.10.2"
+compiler = "3.2.0-alpha11"
 
 [libraries]
 clikt = { module = "com.github.ajalt.clikt:clikt", version.ref = "clikt" }
@@ -19,6 +20,7 @@ mp_bintools = { module = "net.sergeych:mp_bintools", version.ref = "mp_bintools"
 firebase-crashlytics-buildtools = { group = "com.google.firebase", name = "firebase-crashlytics-buildtools", version.ref = "firebaseCrashlyticsBuildtools" }
 okio = { module = "com.squareup.okio:okio", version.ref = "okioVersion" }
 okio-fakefilesystem = { module = "com.squareup.okio:okio-fakefilesystem", version.ref = "okioVersion" }
+compiler = { group = "androidx.databinding", name = "compiler", version.ref = "compiler" }
 
 [plugins]
 androidLibrary = { id = "com.android.library", version.ref = "agp" }

happy.py

@@ -1,11 +0,0 @@
-count = 0
-for n1 in range(10):
-    for n2 in range(10):
-        for n3 in range(10):
-            for n4 in range(10):
-                for n5 in range(10):
-                    for n6 in range(10):
-                        if n1 + n2 + n3 == n4 + n5 + n6:
-                            count += 1
-
-print(count)

library/src/commonMain/kotlin/net/sergeych/lyng/Context.kt

@@ -1,123 +0,0 @@
-package net.sergeych.lyng
-
-class Context(
-    val parent: Context?,
-    val args: Arguments = Arguments.EMPTY,
-    var pos: Pos = Pos.builtIn,
-    val thisObj: Obj = ObjVoid,
-    var skipContextCreation: Boolean = false,
-) {
-    constructor(
-        args: Arguments = Arguments.EMPTY,
-        pos: Pos = Pos.builtIn,
-    )
-            : this(Script.defaultContext, args, pos)
-
-    fun raiseNotImplemented(what: String = "operation"): Nothing = raiseError("$what is not implemented")
-
-    @Suppress("unused")
-    fun raiseNPE(): Nothing = raiseError(ObjNullPointerException(this))
-
-    @Suppress("unused")
-    fun raiseIndexOutOfBounds(message: String = "Index out of bounds"): Nothing =
-        raiseError(ObjIndexOutOfBoundsException(this, message))
-
-    @Suppress("unused")
-    fun raiseArgumentError(message: String = "Illegal argument error"): Nothing =
-        raiseError(ObjIllegalArgumentException(this, message))
-
-    fun raiseClassCastError(msg: String): Nothing = raiseError(ObjClassCastException(this, msg))
-
-    @Suppress("unused")
-    fun raiseSymbolNotFound(name: String): Nothing =
-        raiseError(ObjSymbolNotDefinedException(this, "symbol is not defined: $name"))
-
-    fun raiseError(message: String): Nothing {
-        throw ExecutionError(ObjException(this, message))
-    }
-
-    fun raiseError(obj: ObjException): Nothing {
-        throw ExecutionError(obj)
-    }
-
-    inline fun <reified T : Obj> requiredArg(index: Int): T {
-        if (args.list.size <= index) raiseError("Expected at least ${index + 1} argument, got ${args.list.size}")
-        return (args.list[index] as? T)
-            ?: raiseClassCastError("Expected type ${T::class.simpleName}, got ${args.list[index]::class.simpleName}")
-    }
-
-    inline fun <reified T : Obj> requireOnlyArg(): T {
-        if (args.list.size != 1) raiseError("Expected exactly 1 argument, got ${args.list.size}")
-        return requiredArg(0)
-    }
-
-    @Suppress("unused")
-    fun requireExactCount(count: Int) {
-        if (args.list.size != count) {
-            raiseError("Expected exactly $count arguments, got ${args.list.size}")
-        }
-    }
-
-    inline fun <reified T : Obj> thisAs(): T = (thisObj as? T)
-        ?: raiseClassCastError("Cannot cast ${thisObj.objClass.className} to ${T::class.simpleName}")
-
-    internal val objects = mutableMapOf<String, ObjRecord>()
-
-    operator fun get(name: String): ObjRecord? =
-        objects[name]
-            ?: parent?.get(name)
-
-    fun copy(pos: Pos, args: Arguments = Arguments.EMPTY, newThisObj: Obj? = null): Context =
-        Context(this, args, pos, newThisObj ?: thisObj)
-
-    fun copy(args: Arguments = Arguments.EMPTY, newThisObj: Obj? = null): Context =
-        Context(this, args, pos, newThisObj ?: thisObj)
-
-    fun copy() = Context(this, args, pos, thisObj)
-
-    fun addItem(
-        name: String,
-        isMutable: Boolean,
-        value: Obj,
-        visibility: Visibility = Visibility.Public
-    ): ObjRecord {
-        return ObjRecord(value, isMutable, visibility).also { objects[name] = it }
-    }
-
-    fun getOrCreateNamespace(name: String): ObjClass {
-        val ns = objects.getOrPut(name) { ObjRecord(ObjNamespace(name), isMutable = false) }.value
-        return ns.objClass
-    }
-
-    inline fun addVoidFn(vararg names: String, crossinline fn: suspend Context.() -> Unit) {
-        addFn<ObjVoid>(*names) {
-            fn(this)
-            ObjVoid
-        }
-    }
-
-    inline fun <reified T : Obj> addFn(vararg names: String, crossinline fn: suspend Context.() -> T) {
-        val newFn = object : Statement() {
-            override val pos: Pos = Pos.builtIn
-
-            override suspend fun execute(context: Context): Obj = context.fn()
-
-        }
-        for (name in names) {
-            addItem(
-                name,
-                false,
-                newFn
-            )
-        }
-    }
-
-    fun addConst(name: String, value: Obj) = addItem(name, false, value)
-
-    suspend fun eval(code: String): Obj =
-        Compiler().compile(code.toSource()).execute(this)
-
-    fun containsLocal(name: String): Boolean = name in objects
-
-
-}

library/src/commonMain/kotlin/net/sergeych/lyng/Obj.kt

@@ -1,428 +0,0 @@
-package net.sergeych.lyng
-
-import kotlinx.coroutines.sync.Mutex
-import kotlinx.coroutines.sync.withLock
-import kotlinx.serialization.SerialName
-import kotlinx.serialization.Serializable
-import net.sergeych.bintools.encodeToHex
-import net.sergeych.synctools.ProtectedOp
-import net.sergeych.synctools.withLock
-import kotlin.contracts.ExperimentalContracts
-
-/**
- * Record to store object with access rules, e.g. [isMutable] and access level [visibility].
- */
-data class ObjRecord(
-    var value: Obj,
-    val isMutable: Boolean,
-    val visibility: Visibility = Visibility.Public
-)
-
-/**
- * When we need read-write access to an object in some abstract storage, we need Accessor,
- * as in-site assigning is not always sufficient, in general case we need to replace the object
- * in the storage.
- *
- * Note that assigning new value is more complex than just replacing the object, see how assignment
- * operator is implemented in [Compiler.allOps].
- */
-data class Accessor(
-    val getter: suspend (Context) -> ObjRecord,
-    val setterOrNull: (suspend (Context, Obj) -> Unit)?
-) {
-    /**
-     * Simplified constructor for immutable stores.
-     */
-    constructor(getter: suspend (Context) -> ObjRecord) : this(getter, null)
-
-    /**
-     * Get the setter or throw.
-     */
-    fun setter(pos: Pos) = setterOrNull ?: throw ScriptError(pos, "can't assign value")
-}
-
-open class Obj {
-    var isFrozen: Boolean = false
-
-    private val monitor = Mutex()
-
-    //    private val memberMutex = Mutex()
-    internal var parentInstances: MutableList<Obj> = mutableListOf()
-
-    private val opInstances = ProtectedOp()
-
-    open fun inspect(): String = toString()
-
-    /**
-     * Some objects are by-value, historically [ObjInt] and [ObjReal] are usually treated as such.
-     * When initializing a var with it, by value objects must be copied. By-reference ones aren't.
-     *
-     * Almost all objects are by-reference.
-     */
-    open fun byValueCopy(): Obj = this
-
-    fun isInstanceOf(someClass: Obj) = someClass === objClass || objClass.allParentsSet.contains(someClass)
-
-    suspend fun invokeInstanceMethod(context: Context, name: String, vararg args: Obj): Obj =
-        invokeInstanceMethod(context, name, Arguments(args.toList()))
-
-    suspend inline fun <reified T : Obj> callMethod(
-        context: Context,
-        name: String,
-        args: Arguments = Arguments.EMPTY
-    ): T = invokeInstanceMethod(context, name, args) as T
-
-    open suspend fun invokeInstanceMethod(
-        context: Context,
-        name: String,
-        args: Arguments = Arguments.EMPTY
-    ): Obj =
-        // note that getInstanceMember traverses the hierarchy
-        objClass.getInstanceMember(context.pos, name).value.invoke(context, this, args)
-
-    fun getMemberOrNull(name: String): Obj? = objClass.getInstanceMemberOrNull(name)?.value
-
-    // methods that to override
-
-    open suspend fun compareTo(context: Context, other: Obj): Int {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun contains(context: Context, other: Obj): Boolean {
-        context.raiseNotImplemented()
-    }
-
-    open val asStr: ObjString by lazy {
-        if (this is ObjString) this else ObjString(this.toString())
-    }
-
-    /**
-     * Class of the object: definition of member functions (top-level), etc.
-     * Note that using lazy allows to avoid endless recursion here
-     */
-    open val objClass: ObjClass by lazy {
-        ObjClass("Obj").apply {
-            addFn("toString") {
-                thisObj.asStr
-            }
-            addFn("contains") {
-                ObjBool(thisObj.contains(this, args.firstAndOnly()))
-            }
-        }
-    }
-
-    open suspend fun plus(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun minus(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun mul(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun div(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun mod(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun logicalNot(context: Context): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun logicalAnd(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun logicalOr(context: Context, other: Obj): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun assign(context: Context, other: Obj): Obj? = null
-
-    /**
-     * a += b
-     * if( the operation is not defined, it returns null and the compiler would try
-     * to generate it as 'this = this + other', reassigning its variable
-     */
-    open suspend fun plusAssign(context: Context, other: Obj): Obj? = null
-
-    /**
-     * `-=` operations, see [plusAssign]
-     */
-    open suspend fun minusAssign(context: Context, other: Obj): Obj? = null
-    open suspend fun mulAssign(context: Context, other: Obj): Obj? = null
-    open suspend fun divAssign(context: Context, other: Obj): Obj? = null
-    open suspend fun modAssign(context: Context, other: Obj): Obj? = null
-
-    open suspend fun getAndIncrement(context: Context): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun incrementAndGet(context: Context): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun decrementAndGet(context: Context): Obj {
-        context.raiseNotImplemented()
-    }
-
-    open suspend fun getAndDecrement(context: Context): Obj {
-        context.raiseNotImplemented()
-    }
-
-    fun willMutate(context: Context) {
-        if (isFrozen) context.raiseError("attempt to mutate frozen object")
-    }
-
-    suspend fun <T> sync(block: () -> T): T = monitor.withLock { block() }
-
-    open suspend fun readField(context: Context, name: String): ObjRecord {
-        // could be property or class field:
-        val obj = objClass.getInstanceMemberOrNull(name) ?: context.raiseError("no such field: $name")
-        return when (val value = obj.value) {
-            is Statement -> {
-                ObjRecord(value.execute(context.copy(context.pos, newThisObj = this)), obj.isMutable)
-            }
-            // could be writable property naturally
-//            null -> ObjNull.asReadonly
-            else -> obj
-        }
-    }
-
-    open suspend fun writeField(context: Context, name: String, newValue: Obj) {
-        willMutate(context)
-        val field = objClass.getInstanceMemberOrNull(name) ?: context.raiseError("no such field: $name")
-        if (field.isMutable) field.value = newValue else context.raiseError("can't assign to read-only field: $name")
-    }
-
-    open suspend fun getAt(context: Context, index: Int): Obj {
-        context.raiseNotImplemented("indexing")
-    }
-
-    open suspend fun putAt(context: Context, index: Int, newValue: Obj) {
-        context.raiseNotImplemented("indexing")
-    }
-
-    open suspend fun callOn(context: Context): Obj {
-        context.raiseNotImplemented()
-    }
-
-    suspend fun invoke(context: Context, thisObj: Obj, args: Arguments): Obj =
-        callOn(context.copy(context.pos, args = args, newThisObj = thisObj))
-
-    suspend fun invoke(context: Context, thisObj: Obj, vararg args: Obj): Obj =
-        callOn(
-            context.copy(
-                context.pos,
-                args = Arguments(args.toList()),
-                newThisObj = thisObj
-            )
-        )
-
-    suspend fun invoke(context: Context, thisObj: Obj): Obj =
-        callOn(
-            context.copy(
-                context.pos,
-                args = Arguments.EMPTY,
-                newThisObj = thisObj
-            )
-        )
-
-    suspend fun invoke(context: Context, atPos: Pos, thisObj: Obj, args: Arguments): Obj =
-        callOn(context.copy(atPos, args = args, newThisObj = thisObj))
-
-
-    val asReadonly: ObjRecord by lazy { ObjRecord(this, false) }
-    val asMutable: ObjRecord by lazy { ObjRecord(this, true) }
-
-
-    companion object {
-        inline fun <reified T> from(obj: T): Obj {
-            return when (obj) {
-                is Obj -> obj
-                is Double -> ObjReal(obj)
-                is Float -> ObjReal(obj.toDouble())
-                is Int -> ObjInt(obj.toLong())
-                is Long -> ObjInt(obj)
-                is String -> ObjString(obj)
-                is CharSequence -> ObjString(obj.toString())
-                is Boolean -> ObjBool(obj)
-                Unit -> ObjVoid
-                null -> ObjNull
-                else -> throw IllegalArgumentException("cannot convert to Obj: $obj")
-            }
-        }
-    }
-}
-
-@Suppress("unused")
-inline fun <reified T> T.toObj(): Obj = Obj.from(this)
-
-@Serializable
-@SerialName("void")
-object ObjVoid : Obj() {
-    override fun equals(other: Any?): Boolean {
-        return other is ObjVoid || other is Unit
-    }
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        return if (other === this) 0 else -1
-    }
-
-    override fun toString(): String = "void"
-}
-
-@Serializable
-@SerialName("null")
-object ObjNull : Obj() {
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        return if (other === this) 0 else -1
-    }
-
-    override fun equals(other: Any?): Boolean {
-        return other is ObjNull || other == null
-    }
-
-    override fun toString(): String = "null"
-}
-
-interface Numeric {
-    val longValue: Long
-    val doubleValue: Double
-    val toObjInt: ObjInt
-    val toObjReal: ObjReal
-}
-
-fun Obj.toDouble(): Double =
-    (this as? Numeric)?.doubleValue
-        ?: (this as? ObjString)?.value?.toDouble()
-        ?: throw IllegalArgumentException("cannot convert to double $this")
-
-@Suppress("unused")
-fun Obj.toLong(): Long =
-    when (this) {
-        is Numeric -> longValue
-        is ObjString -> value.toLong()
-        is ObjChar -> value.code.toLong()
-        else -> throw IllegalArgumentException("cannot convert to double $this")
-    }
-
-fun Obj.toInt(): Int = toLong().toInt()
-
-fun Obj.toBool(): Boolean =
-    (this as? ObjBool)?.value ?: throw IllegalArgumentException("cannot convert to boolean $this")
-
-
-data class ObjNamespace(val name: String) : Obj() {
-    override val objClass by lazy { ObjClass(name) }
-
-    override fun inspect(): String = "Ns[$name]"
-
-    override fun toString(): String {
-        return "package $name"
-    }
-}
-
-open class ObjException(exceptionClass: ExceptionClass, val context: Context, val message: String) : Obj() {
-    constructor(name: String,context: Context, message: String) : this(getOrCreateExceptionClass(name), context, message)
-    constructor(context: Context, message: String) : this(Root, context, message)
-
-    fun raise(): Nothing {
-        throw ExecutionError(this)
-    }
-
-    override val objClass: ObjClass = exceptionClass
-
-    override fun toString(): String {
-        return "ObjException:${objClass.className}:${context.pos}@${hashCode().encodeToHex()}"
-    }
-
-    companion object {
-
-        class ExceptionClass(val name: String,vararg parents: ObjClass) : ObjClass(name, *parents) {
-            override suspend fun callOn(context: Context): Obj {
-                val message = context.args.getOrNull(0)?.toString() ?: name
-                return ObjException(this, context, message)
-            }
-            override fun toString(): String = "ExceptionClass[$name]@${hashCode().encodeToHex()}"
-        }
-        val Root = ExceptionClass("Throwable").apply {
-            addConst("message", statement {
-                (thisObj as ObjException).message.toObj()
-            })
-        }
-
-        private val op = ProtectedOp()
-        private val existingErrorClasses = mutableMapOf<String, ExceptionClass>()
-
-
-        @OptIn(ExperimentalContracts::class)
-        protected fun getOrCreateExceptionClass(name: String): ExceptionClass {
-            return op.withLock {
-                existingErrorClasses.getOrPut(name) {
-                    ExceptionClass(name, Root)
-                }
-            }
-        }
-
-        /**
-         * Get [ObjClass] for error class by name if exists.
-         */
-        @OptIn(ExperimentalContracts::class)
-        fun getErrorClass(name: String): ObjClass? = op.withLock {
-            existingErrorClasses[name]
-        }
-
-        fun addExceptionsToContext(context: Context) {
-            context.addConst("Exception", Root)
-            existingErrorClasses["Exception"] = Root
-            for (name in listOf(
-                "NullPointerException",
-                "AssertionFailedException",
-                "ClassCastException",
-                "IndexOutOfBoundsException",
-                "IllegalArgumentException",
-                "IllegalAssignmentException",
-                "SymbolNotDefinedException",
-                "IterationEndException",
-                "AccessException",
-                "UnknownException",
-            )) {
-                context.addConst(name, getOrCreateExceptionClass(name))
-            }
-        }
-    }
-}
-
-class ObjNullPointerException(context: Context) : ObjException("NullPointerException", context, "object is null")
-
-class ObjAssertionFailedException(context: Context, message: String) :
-    ObjException("AssertionFailedException", context, message)
-
-class ObjClassCastException(context: Context, message: String) : ObjException("ClassCastException", context, message)
-class ObjIndexOutOfBoundsException(context: Context, message: String = "index out of bounds") :
-    ObjException("IndexOutOfBoundsException", context, message)
-
-class ObjIllegalArgumentException(context: Context, message: String = "illegal argument") :
-    ObjException("IllegalArgumentException", context, message)
-
-class ObjIllegalAssignmentException(context: Context, message: String = "illegal assignment") :
-    ObjException("IllegalAssignmentException", context, message)
-
-class ObjSymbolNotDefinedException(context: Context, message: String = "symbol is not defined") :
-    ObjException("SymbolNotDefinedException", context, message)
-
-class ObjIterationFinishedException(context: Context) :
-    ObjException("IterationEndException", context, "iteration finished")
-
-class ObjAccessException(context: Context, message: String = "access not allowed error") :
-    ObjException("AccessException", context, message)
-
-class ObjUnknownException(context: Context, message: String = "access not allowed error") :
-    ObjException("UnknownException", context, message)

library/src/commonMain/kotlin/net/sergeych/lyng/ObjBool.kt

@@ -1,27 +0,0 @@
-package net.sergeych.lyng
-
-data class ObjBool(val value: Boolean) : Obj() {
-    override val asStr by lazy { ObjString(value.toString()) }
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        if (other !is ObjBool) return -2
-        return value.compareTo(other.value)
-    }
-
-    override fun toString(): String = value.toString()
-
-    override val objClass: ObjClass = type
-
-    override suspend fun logicalNot(context: Context): Obj = ObjBool(!value)
-
-    override suspend fun logicalAnd(context: Context, other: Obj): Obj = ObjBool(value && other.toBool())
-
-    override suspend fun logicalOr(context: Context, other: Obj): Obj = ObjBool(value || other.toBool())
-
-    companion object {
-        val type = ObjClass("Bool")
-    }
-}
-
-val ObjTrue = ObjBool(true)
-val ObjFalse = ObjBool(false)

library/src/commonMain/kotlin/net/sergeych/lyng/ObjChar.kt

@@ -1,19 +0,0 @@
-package net.sergeych.lyng
-
-class ObjChar(val value: Char): Obj() {
-
-    override val objClass: ObjClass = type
-
-    override suspend fun compareTo(context: Context, other: Obj): Int =
-        (other as? ObjChar)?.let { value.compareTo(it.value) } ?: -1
-
-    override fun toString(): String = value.toString()
-
-    override fun inspect(): String = "'$value'"
-
-    companion object {
-        val type = ObjClass("Char").apply {
-            addFn("code") { ObjInt(thisAs<ObjChar>().value.code.toLong()) }
-        }
-    }
-}

library/src/commonMain/kotlin/net/sergeych/lyng/ObjClass.kt

@@ -1,151 +0,0 @@
-package net.sergeych.lyng
-
-val ObjClassType by lazy { ObjClass("Class") }
-
-open class ObjClass(
-    val className: String,
-    vararg val parents: ObjClass,
-) : Obj() {
-
-    var instanceConstructor: Statement? = null
-
-    val allParentsSet: Set<ObjClass> = parents.flatMap {
-        listOf(it) + it.allParentsSet
-    }.toSet()
-
-    override val objClass: ObjClass by lazy { ObjClassType }
-
-    // members: fields most often
-    private val members = mutableMapOf<String, ObjRecord>()
-
-    override fun toString(): String = className
-
-    override suspend fun compareTo(context: Context, other: Obj): Int = if (other === this) 0 else -1
-
-    override suspend fun callOn(context: Context): Obj {
-        val instance = ObjInstance(this)
-        instance.instanceContext = context.copy(newThisObj = instance,args = context.args)
-        if (instanceConstructor != null) {
-            instanceConstructor!!.execute(instance.instanceContext)
-        }
-        return instance
-    }
-
-    fun defaultInstance(): Obj = object : Obj() {
-        override val objClass: ObjClass = this@ObjClass
-    }
-
-    fun createField(
-        name: String,
-        initialValue: Obj,
-        isMutable: Boolean = false,
-        visibility: Visibility = Visibility.Public,
-        pos: Pos = Pos.builtIn
-    ) {
-        if (name in members || allParentsSet.any { name in it.members })
-            throw ScriptError(pos, "$name is already defined in $objClass or one of its supertypes")
-        members[name] = ObjRecord(initialValue, isMutable, visibility)
-    }
-
-    fun addFn(name: String, isOpen: Boolean = false, code: suspend Context.() -> Obj) {
-        createField(name, statement { code() }, isOpen)
-    }
-
-    fun addConst(name: String, value: Obj) = createField(name, value, isMutable = false)
-
-
-    /**
-     * Get instance member traversing the hierarchy if needed. Its meaning is different for different objects.
-     */
-    fun getInstanceMemberOrNull(name: String): ObjRecord? {
-        members[name]?.let { return it }
-        allParentsSet.forEach { parent -> parent.getInstanceMemberOrNull(name)?.let { return it } }
-        return null
-    }
-
-    fun getInstanceMember(atPos: Pos, name: String): ObjRecord =
-        getInstanceMemberOrNull(name)
-            ?: throw ScriptError(atPos, "symbol doesn't exist: $name")
-}
-
-/**
- * Abstract class that must provide `iterator` method that returns [ObjIterator] instance.
- */
-val ObjIterable by lazy {
-    ObjClass("Iterable").apply {
-
-        addFn("toList") {
-            val result = mutableListOf<Obj>()
-            val iterator = thisObj.invokeInstanceMethod(this, "iterator")
-
-            while (iterator.invokeInstanceMethod(this, "hasNext").toBool())
-                result += iterator.invokeInstanceMethod(this, "next")
-
-
-//        val next = iterator.getMemberOrNull("next")!!
-//        val hasNext = iterator.getMemberOrNull("hasNext")!!
-//        while( hasNext.invoke(this, iterator).toBool() )
-//            result += next.invoke(this, iterator)
-            ObjList(result)
-        }
-
-    }
-}
-
-/**
- * Collection is an iterator with `size`]
- */
-val ObjCollection by lazy {
-    val i: ObjClass = ObjIterable
-    ObjClass("Collection", i)
-}
-
-val ObjIterator by lazy { ObjClass("Iterator") }
-
-class ObjArrayIterator(val array: Obj) : Obj() {
-
-    override val objClass: ObjClass by lazy { type }
-
-    private var nextIndex = 0
-    private var lastIndex = 0
-
-    suspend fun init(context: Context) {
-        nextIndex = 0
-        lastIndex = array.invokeInstanceMethod(context, "size").toInt()
-        ObjVoid
-    }
-
-    companion object {
-        val type by lazy {
-            ObjClass("ArrayIterator", ObjIterator).apply {
-                addFn("next") {
-                    val self = thisAs<ObjArrayIterator>()
-                    if (self.nextIndex < self.lastIndex) {
-                        self.array.invokeInstanceMethod(this, "getAt", (self.nextIndex++).toObj())
-                    } else raiseError(ObjIterationFinishedException(this))
-                }
-                addFn("hasNext") {
-                    val self = thisAs<ObjArrayIterator>()
-                    if (self.nextIndex < self.lastIndex) ObjTrue else ObjFalse
-                }
-            }
-        }
-    }
-}
-
-
-val ObjArray by lazy {
-
-    /**
-     * Array abstract class is a [ObjCollection] with `getAt` method.
-     */
-    ObjClass("Array", ObjCollection).apply {
-        // we can create iterators using size/getat:
-
-        addFn("iterator") {
-            ObjArrayIterator(thisObj).also { it.init(this) }
-        }
-        addFn("isample") { "ok".toObj() }
-    }
-}
-

library/src/commonMain/kotlin/net/sergeych/lyng/ObjInstance.kt

@@ -1,55 +0,0 @@
-package net.sergeych.lyng
-
-class ObjInstance(override val objClass: ObjClass) : Obj() {
-
-    internal lateinit var instanceContext: Context
-
-    override suspend fun readField(context: Context, name: String): ObjRecord {
-        return instanceContext[name]?.let {
-            if (it.visibility.isPublic)
-                it
-            else
-                context.raiseError(ObjAccessException(context, "can't access non-public field $name"))
-        }
-            ?: super.readField(context, name)
-    }
-
-    override suspend fun writeField(context: Context, name: String, newValue: Obj) {
-        instanceContext[name]?.let { f ->
-            if (!f.visibility.isPublic)
-                ObjIllegalAssignmentException(context, "can't assign to non-public field $name")
-            if (!f.isMutable) ObjIllegalAssignmentException(context, "can't reassign val $name").raise()
-            if (f.value.assign(context, newValue) == null)
-                f.value = newValue
-        } ?: super.writeField(context, name, newValue)
-    }
-
-    override suspend fun invokeInstanceMethod(context: Context, name: String, args: Arguments): Obj =
-        instanceContext[name]?.let {
-            if (it.visibility.isPublic)
-                it.value.invoke(context, this, args)
-            else
-                context.raiseError(ObjAccessException(context, "can't invoke non-public method $name"))
-        }
-            ?: super.invokeInstanceMethod(context, name, args)
-
-    private val publicFields: Map<String, ObjRecord>
-        get() = instanceContext.objects.filter { it.value.visibility.isPublic }
-
-    override fun toString(): String {
-        val fields = publicFields.map { "${it.key}=${it.value.value}" }.joinToString(",")
-        return "${objClass.className}($fields)"
-    }
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        if (other !is ObjInstance) return -1
-        if (other.objClass != objClass) return -1
-        for (f in publicFields) {
-            val a = f.value.value
-            val b = other.instanceContext[f.key]!!.value
-            val d = a.compareTo(context, b)
-            if (d != 0) return d
-        }
-        return 0
-    }
-}

library/src/commonMain/kotlin/net/sergeych/lyng/ObjInt.kt

@@ -1,80 +0,0 @@
-package net.sergeych.lyng
-
-data class ObjInt(var value: Long) : Obj(), Numeric {
-    override val asStr get() = ObjString(value.toString())
-    override val longValue get() = value
-    override val doubleValue get() = value.toDouble()
-    override val toObjInt get() = this
-    override val toObjReal = ObjReal(doubleValue)
-
-    override fun byValueCopy(): Obj = ObjInt(value)
-
-    override suspend fun getAndIncrement(context: Context): Obj {
-        return ObjInt(value).also { value++ }
-    }
-
-    override suspend fun getAndDecrement(context: Context): Obj {
-        return ObjInt(value).also { value-- }
-    }
-
-    override suspend fun incrementAndGet(context: Context): Obj {
-        return ObjInt(++value)
-    }
-
-    override suspend fun decrementAndGet(context: Context): Obj {
-        return ObjInt(--value)
-    }
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        if (other !is Numeric) return -2
-        return value.compareTo(other.doubleValue)
-    }
-
-    override fun toString(): String = value.toString()
-
-    override val objClass: ObjClass = type
-
-    override suspend fun plus(context: Context, other: Obj): Obj =
-        if (other is ObjInt)
-            ObjInt(this.value + other.value)
-        else
-            ObjReal(this.doubleValue + other.toDouble())
-
-    override suspend fun minus(context: Context, other: Obj): Obj =
-        if (other is ObjInt)
-            ObjInt(this.value - other.value)
-        else
-            ObjReal(this.doubleValue - other.toDouble())
-
-    override suspend fun mul(context: Context, other: Obj): Obj =
-        if (other is ObjInt) {
-            ObjInt(this.value * other.value)
-        } else ObjReal(this.value * other.toDouble())
-
-    override suspend fun div(context: Context, other: Obj): Obj =
-        if (other is ObjInt)
-            ObjInt(this.value / other.value)
-        else ObjReal(this.value / other.toDouble())
-
-    override suspend fun mod(context: Context, other: Obj): Obj =
-        if (other is ObjInt)
-            ObjInt(this.value % other.value)
-        else ObjReal(this.value.toDouble() % other.toDouble())
-
-    /**
-     * We are by-value type ([byValueCopy] is implemented) so we can do in-place
-     * assignment
-     */
-    override suspend fun assign(context: Context, other: Obj): Obj? {
-        return if (other is ObjInt) {
-            value = other.value
-            this
-        } else null
-    }
-
-    companion object {
-        val type = ObjClass("Int")
-    }
-}
-
-fun Int.toObj() = ObjInt(this.toLong())

library/src/commonMain/kotlin/net/sergeych/lyng/ObjList.kt

@@ -1,137 +0,0 @@
-package net.sergeych.lyng
-
-class ObjList(val list: MutableList<Obj> = mutableListOf()) : Obj() {
-
-    init {
-        for (p in objClass.parents)
-            parentInstances.add(p.defaultInstance())
-    }
-
-    override fun toString(): String = "[${
-        list.joinToString(separator = ", ") { it.inspect() }
-    }]"
-
-    fun normalize(context: Context, index: Int, allowisEndInclusive: Boolean = false): Int {
-        val i = if (index < 0) list.size + index else index
-        if (allowisEndInclusive && i == list.size) return i
-        if (i !in list.indices) context.raiseError("index $index out of bounds for size ${list.size}")
-        return i
-    }
-
-    override suspend fun getAt(context: Context, index: Int): Obj {
-        val i = normalize(context, index)
-        return list[i]
-    }
-
-    override suspend fun putAt(context: Context, index: Int, newValue: Obj) {
-        val i = normalize(context, index)
-        list[i] = newValue
-    }
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        if (other !is ObjList) return -2
-        val mySize = list.size
-        val otherSize = other.list.size
-        val commonSize = minOf(mySize, otherSize)
-        for (i in 0..<commonSize) {
-            if (list[i].compareTo(context, other.list[i]) != 0) {
-                return list[i].compareTo(context, other.list[i])
-            }
-        }
-        // equal so far, longer is greater:
-        return when {
-            mySize < otherSize -> -1
-            mySize > otherSize -> 1
-            else -> 0
-        }
-    }
-
-    override suspend fun plus(context: Context, other: Obj): Obj =
-        when {
-            other is ObjList ->
-                ObjList((list + other.list).toMutableList())
-
-            other.isInstanceOf(ObjIterable) -> {
-                val l = other.callMethod<ObjList>(context, "toList")
-                ObjList((list + l.list).toMutableList())
-            }
-
-            else ->
-                context.raiseError("'+': can't concatenate $this with $other")
-        }
-
-
-    override suspend fun plusAssign(context: Context, other: Obj): Obj {
-        // optimization
-        if (other is ObjList) {
-            list += other.list
-            return this
-        }
-        if (other.isInstanceOf(ObjIterable)) {
-            val otherList = other.invokeInstanceMethod(context, "toList") as ObjList
-            list += otherList.list
-        } else
-            list += other
-        return this
-    }
-
-    override val objClass: ObjClass
-        get() = type
-
-    companion object {
-        val type = ObjClass("List", ObjArray).apply {
-
-            createField("size",
-                statement {
-                    (thisObj as ObjList).list.size.toObj()
-                }
-            )
-            addFn("getAt") {
-                requireExactCount(1)
-                thisAs<ObjList>().getAt(this, requiredArg<ObjInt>(0).value.toInt())
-            }
-            addFn("putAt") {
-                requireExactCount(2)
-                val newValue = args[1]
-                thisAs<ObjList>().putAt(this, requiredArg<ObjInt>(0).value.toInt(), newValue)
-                newValue
-            }
-            createField("add",
-                statement {
-                    val l = thisAs<ObjList>().list
-                    for (a in args) l.add(a)
-                    ObjVoid
-                }
-            )
-            createField("addAt",
-                statement {
-                    if (args.size < 2) raiseError("addAt takes 2+ arguments")
-                    val l = thisAs<ObjList>()
-                    var index = l.normalize(
-                        this, requiredArg<ObjInt>(0).value.toInt(),
-                        allowisEndInclusive = true
-                    )
-                    for (i in 1..<args.size) l.list.add(index++, args[i])
-                    ObjVoid
-                }
-            )
-            addFn("removeAt") {
-                val self = thisAs<ObjList>()
-                val start = self.normalize(this, requiredArg<ObjInt>(0).value.toInt())
-                if (args.size == 2) {
-                    val end = requireOnlyArg<ObjInt>().value.toInt()
-                    self.list.subList(start, self.normalize(this, end)).clear()
-                } else
-                    self.list.removeAt(start)
-                self
-            }
-            addFn("removeRangeInclusive") {
-                val self = thisAs<ObjList>()
-                val start = self.normalize(this, requiredArg<ObjInt>(0).value.toInt())
-                val end = self.normalize(this, requiredArg<ObjInt>(1).value.toInt()) + 1
-                self.list.subList(start, end).clear()
-                self
-            }
-        }
-    }
-}

library/src/commonMain/kotlin/net/sergeych/lyng/ObjReal.kt

@@ -1,49 +0,0 @@
-package net.sergeych.lyng
-
-import kotlin.math.floor
-import kotlin.math.roundToLong
-
-data class ObjReal(val value: Double) : Obj(), Numeric {
-    override val asStr by lazy { ObjString(value.toString()) }
-    override val longValue: Long by lazy { floor(value).toLong() }
-    override val doubleValue: Double by lazy { value }
-    override val toObjInt: ObjInt by lazy { ObjInt(longValue) }
-    override val toObjReal: ObjReal by lazy { ObjReal(value) }
-
-    override fun byValueCopy(): Obj = ObjReal(value)
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        if (other !is Numeric) return -2
-        return value.compareTo(other.doubleValue)
-    }
-
-    override fun toString(): String = value.toString()
-
-    override val objClass: ObjClass = type
-
-    override suspend fun plus(context: Context, other: Obj): Obj =
-        ObjReal(this.value + other.toDouble())
-
-    override suspend fun minus(context: Context, other: Obj): Obj =
-        ObjReal(this.value - other.toDouble())
-
-    override suspend fun mul(context: Context, other: Obj): Obj =
-        ObjReal(this.value * other.toDouble())
-
-    override suspend fun div(context: Context, other: Obj): Obj =
-        ObjReal(this.value / other.toDouble())
-
-    override suspend fun mod(context: Context, other: Obj): Obj =
-        ObjReal(this.value % other.toDouble())
-
-    companion object {
-        val type: ObjClass = ObjClass("Real").apply {
-            createField(
-                "roundToInt",
-                statement(Pos.builtIn) {
-                    (it.thisObj as ObjReal).value.roundToLong().toObj()
-                },
-            )
-        }
-    }
-}

library/src/commonMain/kotlin/net/sergeych/lyng/ObjString.kt

@@ -1,72 +0,0 @@
-package net.sergeych.lyng
-
-import kotlinx.serialization.SerialName
-import kotlinx.serialization.Serializable
-
-@Serializable
-@SerialName("string")
-data class ObjString(val value: String) : Obj() {
-
-    override suspend fun compareTo(context: Context, other: Obj): Int {
-        if (other !is ObjString) return -2
-        return this.value.compareTo(other.value)
-    }
-
-    override fun toString(): String = value
-
-    override val asStr: ObjString by lazy { this }
-
-    override fun inspect(): String {
-        return "\"$value\""
-    }
-
-    override val objClass: ObjClass
-        get() = type
-
-    override suspend fun plus(context: Context, other: Obj): Obj {
-        return ObjString(value + other.asStr.value)
-    }
-
-    override suspend fun getAt(context: Context, index: Int): Obj {
-        return ObjChar(value[index])
-    }
-
-    companion object {
-        val type = ObjClass("String").apply {
-            addConst("startsWith",
-                statement {
-                    ObjBool(thisAs<ObjString>().value.startsWith(requiredArg<ObjString>(0).value))
-                })
-            addConst("length",
-                statement { ObjInt(thisAs<ObjString>().value.length.toLong()) }
-            )
-            addFn("takeLast") {
-                thisAs<ObjString>().value.takeLast(
-                    requiredArg<ObjInt>(0).toInt()
-                ).let(::ObjString)
-            }
-            addFn("take") {
-                thisAs<ObjString>().value.take(
-                    requiredArg<ObjInt>(0).toInt()
-                ).let(::ObjString)
-            }
-            addFn("drop") {
-                thisAs<ObjString>().value.drop(
-                    requiredArg<ObjInt>(0).toInt()
-                ).let(::ObjString)
-            }
-            addFn("dropLast") {
-                thisAs<ObjString>().value.dropLast(
-                    requiredArg<ObjInt>(0).toInt()
-                ).let(::ObjString)
-            }
-            addFn("lower") {
-                thisAs<ObjString>().value.lowercase().let(::ObjString)
-            }
-            addFn("upper") {
-                thisAs<ObjString>().value.uppercase().let(::ObjString)
-            }
-            addFn("size") { ObjInt(thisAs<ObjString>().value.length.toLong()) }
-        }
-    }
-}

library/src/commonMain/kotlin/net/sergeych/lyng/Source.kt

@@ -1,15 +0,0 @@
-package net.sergeych.lyng
-
-class Source(val fileName: String, text: String) {
-
-    val lines = text.lines().map { it.trimEnd() }
-
-    companion object {
-        val builtIn: Source by lazy { Source("built-in", "") }
-        val UNKNOWN: Source by lazy { Source("UNKNOWN", "") }
-    }
-
-    val startPos: Pos = Pos(this, 0, 0)
-
-    fun posAt(line: Int, column: Int): Pos = Pos(this, line, column)
-}

library/src/commonMain/kotlin/net/sergeych/lyng/SymbolSpace.kt

@@ -1,13 +0,0 @@
-package net.sergeych.lyng
-
-
-
-class Symbols(
-    unitType: UnitType,
-    val name: String,
-    val x: TypeDecl
-) {
-    enum class UnitType {
-        Module, Function, Lambda
-    }
-}

library/src/commonMain/kotlin/net/sergeych/lyng/TypeDecl.kt

@@ -1,21 +0,0 @@
-package net.sergeych.lyng
-
-sealed class TypeDecl {
-    // ??
-    data class Fn(val argTypes: List<ArgsDeclaration.Item>, val retType: TypeDecl) : TypeDecl()
-    object Obj : TypeDecl()
-}
-
-/*
-To use in the compiler, we need symbol information when:
-
-- declaring a class: the only way to export its public/protected symbols is to know it in compiler time
-- importing a module: actually,  we cam try to do it in a more efficient way.
-
-Importing module:
-
-The moudule is efficiently a statement, that initializes it with all its symbols modifying some context.
-
-The thing is, we need only
-
- */

lyng/build.gradle.kts

@@ -29,11 +29,11 @@ kotlin {
     sourceSets {
         val commonMain by getting {
             dependencies {
-                implementation(project(":library"))
+                implementation(kotlin("stdlib-common"))
+                implementation(project(":lynglib"))
                 implementation(libs.okio)
-
                 implementation(libs.clikt)
-
+                implementation(kotlin("stdlib-common"))
                 // optional support for rendering markdown in help messages
 //                implementation(libs.clikt.markdown)
             }
@@ -42,9 +42,15 @@ kotlin {
             dependencies {
                 implementation(kotlin("test-common"))
                 implementation(kotlin("test-annotations-common"))
+                implementation(libs.kotlinx.coroutines.core)
                 implementation(libs.okio.fakefilesystem)
             }
         }
+//        val nativeMain by getting {
+//            dependencies {
+//                implementation(kotlin("stdlib-common"))
+//            }
+//        }
         val linuxX64Main by getting {
 
         }

lyng/src/commonMain/kotlin/Common.kt

@@ -1,12 +1,19 @@
 package net.sergeych
 
 import com.github.ajalt.clikt.core.CliktCommand
+import com.github.ajalt.clikt.core.Context
+import com.github.ajalt.clikt.core.main
 import com.github.ajalt.clikt.parameters.arguments.argument
 import com.github.ajalt.clikt.parameters.arguments.multiple
 import com.github.ajalt.clikt.parameters.arguments.optional
 import com.github.ajalt.clikt.parameters.options.flag
 import com.github.ajalt.clikt.parameters.options.option
-import net.sergeych.lyng.*
+import kotlinx.coroutines.runBlocking
+import net.sergeych.lyng.LyngVersion
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.ScriptError
+import net.sergeych.lyng.Source
+import net.sergeych.lyng.obj.*
 import okio.FileSystem
 import okio.Path.Companion.toPath
 import okio.SYSTEM
@@ -17,14 +24,47 @@ import okio.use
 
 expect fun exit(code: Int)
 
-val baseContext = Context().apply {
+expect class ShellCommandExecutor {
+    fun executeCommand(command: String): CommandResult
+
+    companion object {
+        fun create(): ShellCommandExecutor
+    }
+}
+
+data class CommandResult(
+    val exitCode: Int,
+    val output: String,
+    val error: String
+)
+
+val baseScope = Scope().apply {
     addFn("exit") {
         exit(requireOnlyArg<ObjInt>().toInt())
         ObjVoid
     }
+//    ObjString.type.addFn("shell") {
+//
+//    }
 }
 
-class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
+fun runMain(args: Array<String>) {
+    if(args.isNotEmpty()) {
+        if( args.size >= 2 && args[0] == "--" ) {
+            // -- -file.lyng <args>
+            executeFileWithArgs(args[1], args.drop(2))
+            return
+        } else if( args[0][0] != '-') {
+            // file.lyng <args>
+            executeFileWithArgs(args[0], args.drop(1))
+            return
+        }
+    }
+    // normal processing
+    Lyng { runBlocking { it() } }.main(args)
+}
+
+private class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
 
     override val printHelpOnEmptyArgs = true
 
@@ -38,7 +78,7 @@ class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
 
     val args by argument(help = "arguments for script").multiple()
 
-    override fun help(context: com.github.ajalt.clikt.core.Context): String =
+    override fun help(context: Context): String =
         """
             The Lyng script language interpreter, language version is $LyngVersion.
             
@@ -57,7 +97,7 @@ class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
                 val objargs = mutableListOf<String>()
                 script?.let { objargs += it }
                 objargs += args
-                baseContext.addConst(
+                baseScope.addConst(
                     "ARGV", ObjList(
                         objargs.map { ObjString(it) }.toMutableList()
                     )
@@ -65,7 +105,7 @@ class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
                 launcher {
                     // there is no script name, it is a first argument instead:
                     processErrors {
-                        baseContext.eval(execute!!)
+                        baseScope.eval(execute!!)
                     }
                 }
             }
@@ -81,7 +121,7 @@ class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
                     )
                     echoFormattedHelp()
                 } else {
-                    baseContext.addConst("ARGV", ObjList(args.map { ObjString(it) }.toMutableList()))
+                    baseScope.addConst("ARGV", ObjList(args.map { ObjString(it) }.toMutableList()))
                     launcher { executeFile(script!!) }
                 }
             }
@@ -89,14 +129,26 @@ class Lyng(val launcher: (suspend () -> Unit) -> Unit) : CliktCommand() {
     }
 }
 
+fun executeFileWithArgs(fileName: String, args: List<String>) {
+    runBlocking {
+        baseScope.addConst("ARGV", ObjList(args.map { ObjString(it) }.toMutableList()))
+        executeFile(fileName)
+    }
+}
+
 suspend fun executeFile(fileName: String) {
-    val text = FileSystem.SYSTEM.source(fileName.toPath()).use { fileSource ->
+    var text = FileSystem.SYSTEM.source(fileName.toPath()).use { fileSource ->
         fileSource.buffer().use { bs ->
             bs.readUtf8()
         }
     }
+    if( text.startsWith("#!") ) {
+        // skip shebang
+        val pos = text.indexOf('\n')
+        text = text.substring(pos + 1)
+    }
     processErrors {
-        Compiler().compile(Source(fileName, text)).execute(baseContext)
+        baseScope.eval(Source(fileName, text))
     }
 }
 

lyng/src/jvmMain/kotlin/Shell.jvm.kt

@@ -0,0 +1,23 @@
+@file:Suppress("EXPECT_ACTUAL_CLASSIFIERS_ARE_IN_BETA_WARNING")
+
+package net.sergeych
+
+// Alternative implementation for native targets
+actual class ShellCommandExecutor() {
+    actual fun executeCommand(command: String): CommandResult {
+        val process = ProcessBuilder("/bin/sh", "-c", command).start()
+        val exitCode = process.waitFor()
+        val output = process.inputStream.bufferedReader().readText()
+        val error = process.errorStream.bufferedReader().readText()
+
+        return CommandResult(
+            exitCode = exitCode,
+            output = output.trim(),
+            error = error.trim()
+        )
+    }
+
+    actual companion object {
+        actual fun create(): ShellCommandExecutor = ShellCommandExecutor()
+    }
+}

lyng/src/jvmMain/kotlin/net/sergeych/lyng_cli/Main.kt

@@ -1,9 +1,7 @@
 package net.sergeych.lyng_cli
 
-import com.github.ajalt.clikt.core.main
-import kotlinx.coroutines.runBlocking
-import net.sergeych.Lyng
+import net.sergeych.runMain
 
 fun main(args: Array<String>) {
-    Lyng({ runBlocking { it() } }).main(args)
+    runMain(args)
 }

lyng/src/linuxX64Main/kotlin/Main.kt

@@ -1,7 +1,5 @@
-import com.github.ajalt.clikt.core.main
-import kotlinx.coroutines.runBlocking
-import net.sergeych.Lyng
+import net.sergeych.runMain
 
 fun main(args: Array<String>) {
-    Lyng( { runBlocking { it() } }).main(args)
+    runMain(args)
 }

lyng/src/nativeMain/kotlin/Common.native.kt

@@ -1,7 +1,48 @@
+@file:OptIn(ExperimentalForeignApi::class, ExperimentalForeignApi::class, ExperimentalForeignApi::class)
+
 package net.sergeych
 
+import kotlinx.cinterop.*
+import platform.posix.fgets
+import platform.posix.pclose
+import platform.posix.popen
 import kotlin.system.exitProcess
 
+actual class ShellCommandExecutor() {
+    actual fun executeCommand(command: String): CommandResult {
+        val outputBuilder = StringBuilder()
+        val errorBuilder = StringBuilder()
+
+        val fp = popen(command, "r") ?: return CommandResult(
+            exitCode = -1,
+            output = "",
+            error = "Failed to execute command"
+        )
+
+        val buffer = ByteArray(4096)
+        while (true) {
+            val bytesRead = buffer.usePinned { pinned ->
+                fgets(pinned.addressOf(0), buffer.size.convert(), fp)
+            }
+            if (bytesRead == null) break
+            outputBuilder.append(bytesRead.toKString())
+        }
+
+        val status = pclose(fp)
+        val exitCode = if (status == 0) 0 else 1
+
+        return CommandResult(
+            exitCode = exitCode,
+            output = outputBuilder.toString().trim(),
+            error = errorBuilder.toString().trim()
+        )
+    }
+
+    actual companion object {
+        actual fun create(): ShellCommandExecutor = ShellCommandExecutor()
+    }
+}
+
 actual fun exit(code: Int) {
     exitProcess(code)
 }

lynglib/build.gradle.kts

@@ -1,11 +1,10 @@
 import com.codingfeline.buildkonfig.compiler.FieldSpec.Type.STRING
-import com.vanniktech.maven.publish.SonatypeHost
 import org.jetbrains.kotlin.gradle.ExperimentalKotlinGradlePluginApi
 import org.jetbrains.kotlin.gradle.ExperimentalWasmDsl
 import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 
 group = "net.sergeych"
-version = "0.5.1-SNAPSHOT"
+version = "0.8.1-SNAPSHOT"
 
 buildscript {
     repositories {
@@ -20,9 +19,10 @@ buildscript {
 plugins {
     alias(libs.plugins.kotlinMultiplatform)
     alias(libs.plugins.androidLibrary)
-    alias(libs.plugins.vanniktech.mavenPublish)
-    kotlin("plugin.serialization") version "2.1.20"
+//    alias(libs.plugins.vanniktech.mavenPublish)
+    kotlin("plugin.serialization") version "2.2.0"
     id("com.codingfeline.buildkonfig") version "0.17.1"
+    `maven-publish`
 }
 
 buildkonfig {
@@ -62,7 +62,7 @@ kotlin {
     sourceSets {
         all {
             languageSettings.optIn("kotlinx.coroutines.ExperimentalCoroutinesApi")
-            languageSettings.optIn("kotlin.contracts.ExperimentalContracts::class")
+            languageSettings.optIn("kotlin.contracts.ExperimentalContracts")
             languageSettings.optIn("kotlin.ExperimentalUnsignedTypes")
             languageSettings.optIn("kotlin.coroutines.DelicateCoroutinesApi")
         }
@@ -99,75 +99,57 @@ android {
 }
 dependencies {
     implementation(libs.firebase.crashlytics.buildtools)
+    implementation(libs.compiler)
 }
 
-mavenPublishing {
-    publishToMavenCentral(SonatypeHost.CENTRAL_PORTAL)
+publishing {
+    val mavenToken by lazy {
+        File("${System.getProperty("user.home")}/.gitea_token").readText()
+    }
+    repositories {
+        maven {
+            credentials(HttpHeaderCredentials::class) {
+                name = "Authorization"
+                value = mavenToken
+            }
+            url = uri("https://gitea.sergeych.net/api/packages/SergeychWorks/maven")
+            authentication {
+                create("Authorization", HttpHeaderAuthentication::class)
+            }
+        }
+    }
+}
 
-    signAllPublications()
-
-    coordinates(group.toString(), "library", version.toString())
-
-    pom {
-        name = "Lyng language"
-        description = "Kotlin-bound scripting loanguage"
-        inceptionYear = "2025"
-//        url = "https://sergeych.net"
-        licenses {
-            license {
-                name = "XXX"
-                url = "YYY"
-                distribution = "ZZZ"
-            }
-        }
-        developers {
-            developer {
-                id = "XXX"
-                name = "YYY"
-                url = "ZZZ"
-            }
-        }
-        scm {
-            url = "XXX"
-            connection = "YYY"
-            developerConnection = "ZZZ"
-        }
-    }
-}
+//mavenPublishing {
+//    publishToMavenCentral(SonatypeHost.CENTRAL_PORTAL)
 //
-//val projectVersion  by project.extra(provider {
-//    // Compute value lazily
-//    (version as String)
-//})
+//    signAllPublications()
 //
-//val generateBuildConfig by tasks.registering {
-//    // Declare outputs safely
-//    val outputDir = layout.buildDirectory.dir("generated/buildConfig/commonMain/kotlin")
-//    outputs.dir(outputDir)
+//    coordinates(group.toString(), "library", version.toString())
 //
-//    val version = projectVersion.get()
-//
-//    // Inputs: Version is tracked as an input
-//    inputs.property("version", version)
-//
-//    doLast {
-//        val packageName = "net.sergeych.lyng.buildconfig"
-//        val packagePath = packageName.replace('.', '/')
-//        val buildConfigFile = outputDir.get().file("$packagePath/BuildConfig.kt").asFile
-//
-//        buildConfigFile.parentFile?.mkdirs()
-//        buildConfigFile.writeText(
-//            """
-//            |package $packageName
-//            |
-//            |object BuildConfig {
-//            |    const val VERSION = "$version"
-//            |}
-//            """.trimMargin()
-//        )
+//    pom {
+//        name = "Lyng language"
+//        description = "Kotlin-bound scripting loanguage"
+//        inceptionYear = "2025"
+////        url = "https://sergeych.net"
+//        licenses {
+//            license {
+//                name = "XXX"
+//                url = "YYY"
+//                distribution = "ZZZ"
+//            }
+//        }
+//        developers {
+//            developer {
+//                id = "XXX"
+//                name = "YYY"
+//                url = "ZZZ"
+//            }
+//        }
+//        scm {
+//            url = "XXX"
+//            connection = "YYY"
+//            developerConnection = "ZZZ"
 //        }
 //    }
-//
-//tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {
-//    dependsOn(generateBuildConfig)
 //}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/AppliedScope.kt

@@ -0,0 +1,19 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.ObjRecord
+
+/**
+ * Special version of the [Scope] used to `apply` new this object to
+ * _parent context property.
+ *
+ * @param _parent context to apply to
+ * @param args arguments for the new context
+ * @param appliedScope the new context to apply, it will have lower priority except for `this` which
+ *      will be reset by appliedContext's `this`.
+ */
+class AppliedScope(_parent: Scope, args: Arguments, val appliedScope: Scope)
+    : Scope(_parent, args, appliedScope.pos, appliedScope.thisObj) {
+    override fun get(name: String): ObjRecord? =
+        if (name == "this") thisObj.asReadonly
+        else super.get(name) ?: appliedScope[name]
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/ArgsDeclaration.kt

@@ -1,5 +1,9 @@
 package net.sergeych.lyng
 
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjList
+import net.sergeych.lyng.obj.ObjRecord
+
 /**
  * List of argument declarations in the __definition__ of the lambda, class constructor,
  * function, etc. It is created by [Compiler.parseArgsDeclaration]
@@ -19,17 +23,20 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
     }
 
     /**
-     * parse args and create local vars in a given context
+     * parse args and create local vars in a given context properly interpreting
+     * ellipsis args and default values
      */
     suspend fun assignToContext(
-        context: Context,
-        arguments: Arguments = context.args,
+        scope: Scope,
+        arguments: Arguments = scope.args,
         defaultAccessType: AccessType = AccessType.Var,
-        defaultVisibility: Visibility = Visibility.Public
+        defaultVisibility: Visibility = Visibility.Public,
+        defaultRecordType: ObjRecord.Type = ObjRecord.Type.ConstructorField
     ) {
         fun assign(a: Item, value: Obj) {
-            context.addItem(a.name, (a.accessType ?: defaultAccessType).isMutable, value,
-                a.visibility ?: defaultVisibility)
+            scope.addItem(a.name, (a.accessType ?: defaultAccessType).isMutable, value,
+                a.visibility ?: defaultVisibility,
+                recordType = defaultRecordType)
         }
 
         // will be used with last lambda arg fix
@@ -52,11 +59,11 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
                 if (a.isEllipsis) break
                 val value = when {
                     i < callArgs.size -> callArgs[i]
-                    a.defaultValue != null -> a.defaultValue.execute(context)
+                    a.defaultValue != null -> a.defaultValue.execute(scope)
                     else -> {
-                        println("callArgs: ${callArgs.joinToString()}")
-                        println("tailBlockMode: ${arguments.tailBlockMode}")
-                        context.raiseArgumentError("too few arguments for the call")
+//                        println("callArgs: ${callArgs.joinToString()}")
+//                        println("tailBlockMode: ${arguments.tailBlockMode}")
+                        scope.raiseIllegalArgument("too few arguments for the call")
                     }
                 }
                 assign(a, value)
@@ -76,8 +83,8 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
                         callArgs[j--]
                     }
 
-                    a.defaultValue != null -> a.defaultValue.execute(context)
-                    else -> context.raiseArgumentError("too few arguments for the call")
+                    a.defaultValue != null -> a.defaultValue.execute(scope)
+                    else -> scope.raiseIllegalArgument("too few arguments for the call")
                 }
                 assign(a, value)
                 i--
@@ -98,7 +105,7 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
             processEllipsis(leftIndex, end)
         } else {
             if (leftIndex < callArgs.size)
-                context.raiseArgumentError("too many arguments for the call")
+                scope.raiseIllegalArgument("too many arguments for the call")
         }
     }
 
@@ -110,7 +117,7 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
      */
     data class Item(
         val name: String,
-        val type: TypeDecl = TypeDecl.Obj,
+        val type: TypeDecl = TypeDecl.TypeAny,
         val pos: Pos = Pos.builtIn,
         val isEllipsis: Boolean = false,
         /**

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Arguments.kt

@@ -1,12 +1,16 @@
 package net.sergeych.lyng
 
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjIterable
+import net.sergeych.lyng.obj.ObjList
+
 data class ParsedArgument(val value: Statement, val pos: Pos, val isSplat: Boolean = false)
 
-suspend fun Collection<ParsedArgument>.toArguments(context: Context,tailBlockMode: Boolean): Arguments {
+suspend fun Collection<ParsedArgument>.toArguments(scope: Scope, tailBlockMode: Boolean): Arguments {
     val list = mutableListOf<Obj>()
 
     for (x in this) {
-        val value = x.value.execute(context)
+        val value = x.value.execute(scope)
         if (x.isSplat) {
             when {
                 value is ObjList -> {
@@ -14,11 +18,11 @@ suspend fun Collection<ParsedArgument>.toArguments(context: Context,tailBlockMod
                 }
 
                 value.isInstanceOf(ObjIterable) -> {
-                    val i = (value.invokeInstanceMethod(context, "toList") as ObjList).list
+                    val i = (value.invokeInstanceMethod(scope, "toList") as ObjList).list
                     i.forEach { list.add(it) }
                 }
 
-                else -> context.raiseClassCastError("expected list of objects for splat argument")
+                else -> scope.raiseClassCastError("expected list of objects for splat argument")
             }
         } else
             list.add(value)
@@ -28,11 +32,23 @@ suspend fun Collection<ParsedArgument>.toArguments(context: Context,tailBlockMod
 
 data class Arguments(val list: List<Obj>, val tailBlockMode: Boolean = false) : List<Obj> by list {
 
+    constructor(vararg values: Obj) : this(values.toList())
+
     fun firstAndOnly(pos: Pos = Pos.UNKNOWN): Obj {
         if (list.size != 1) throw ScriptError(pos, "expected one argument, got ${list.size}")
         return list.first()
     }
 
+    /**
+     * Convert to list of kotlin objects, see [Obj.toKotlin].
+     */
+    suspend fun toKotlinList(scope: Scope): List<Any?> {
+        return list.map { it.toKotlin(scope) }
+    }
+
+    fun inspect(): String = list.joinToString(", ") { it.inspect() }
+
+
     companion object {
         val EMPTY = Arguments(emptyList())
         fun from(values: Collection<Obj>) = Arguments(values.toList())

lynglib/src/commonMain/kotlin/net/sergeych/lyng/CompilerContext.kt

@@ -1,13 +1,11 @@
 package net.sergeych.lyng
 
-internal class CompilerContext(val tokens: List<Token>) {
+class CompilerContext(val tokens: List<Token>) {
     val labels = mutableSetOf<String>()
 
     var breakFound = false
-        private set
 
     var loopLevel = 0
-        private set
 
     inline fun <T> parseLoop(f: () -> T): Pair<Boolean, T> {
         if (++loopLevel == 0) breakFound = false
@@ -21,7 +19,11 @@ internal class CompilerContext(val tokens: List<Token>) {
 
     fun hasNext() = currentIndex < tokens.size
     fun hasPrevious() = currentIndex > 0
-    fun next() = tokens.getOrElse(currentIndex) { throw IllegalStateException("No next token") }.also { currentIndex++ }
+    fun next() =
+        if( currentIndex < tokens.size ) tokens[currentIndex++]
+        else Token("", tokens.last().pos, Token.Type.EOF)
+//        throw IllegalStateException("No more tokens")
+
     fun previous() = if (!hasPrevious()) throw IllegalStateException("No previous token") else tokens[--currentIndex]
 
     fun savePos() = currentIndex
@@ -47,9 +49,25 @@ internal class CompilerContext(val tokens: List<Token>) {
         throw ScriptError(at, message)
     }
 
-    fun currentPos() =
-        if (hasNext()) next().pos.also { previous() }
-        else previous().pos.also { next() }
+    fun syntaxError(message: String = "Syntax error"): Nothing {
+        throw ScriptError(currentPos(), message)
+    }
+
+    fun currentPos(): Pos = tokens[currentIndex].pos
+
+    /**
+     * If the next token is identifier `name`, skip it and return `true`.
+     * else leave where it is and return `false`
+     */
+    fun skipId(name: String): Boolean {
+        current().let { t ->
+            if( t.type == Token.Type.ID && t.value == name ) {
+                next()
+                return true
+            }
+        }
+        return false
+    }
 
     /**
      * Skips next token if its type is `tokenType`, returns `true` if so.
@@ -83,7 +101,7 @@ internal class CompilerContext(val tokens: List<Token>) {
     }
 
 
-    fun ifNextIs(typeId: Token.Type, f: (Token) -> Unit): Boolean {
+    inline fun ifNextIs(typeId: Token.Type, f: (Token) -> Unit): Boolean {
         val t = next()
         return if (t.type == typeId) {
             f(t)
@@ -102,6 +120,7 @@ internal class CompilerContext(val tokens: List<Token>) {
      * Return value of the next token if it is an identifier, null otherwise.
      * Does not change position.
      */
+    @Suppress("unused")
     fun nextIdValue(): String? {
         return if (hasNext()) {
             val nt = tokens[currentIndex]
@@ -117,36 +136,45 @@ internal class CompilerContext(val tokens: List<Token>) {
     /**
      * If the token at current position plus offset (could be negative) exists, returns it, otherwise returns null.
      */
+    @Suppress("unused")
     fun atOffset(offset: Int): Token? =
         if (currentIndex + offset in tokens.indices) tokens[currentIndex + offset] else null
 
+    fun matchQualifiers(keyword: String, vararg qualifiers: String): Boolean {
+        val pos = savePos()
+        var count = 0
+        while( count < qualifiers.size) {
+            val t = next()
+            when(t.type) {
+                Token.Type.ID -> {
+                    if( t.value in qualifiers ) count++
+                    else { restorePos(pos); return false }
+                }
+                Token.Type.MULTILINE_COMMENT, Token.Type.SINLGE_LINE_COMMENT, Token.Type.NEWLINE -> {}
+                else -> { restorePos(pos); return false }
+            }
+        }
+        val t = next()
+        if( t.type == Token.Type.ID && t.value == keyword ) {
+            return true
+        } else {
+            restorePos(pos)
+            return false
+        }
+    }
+
     /**
-     * Scan backwards as deep as specified looking for visibility token. Does not change position.
+     * Skip newlines and comments. Returns (and reads) first non-whitespace token.
+     * Note that [Token.Type.EOF] is not considered a whitespace token.
      */
-    fun getVisibility(default: Visibility = Visibility.Public, depths: Int = 2): Visibility {
-        for( i in -depths .. -1) {
-            when( atOffset(i)?.type) {
-                Token.Type.PROTECTED -> return Visibility.Protected
-                Token.Type.PRIVATE -> return Visibility.Private
-                else -> {}
+    fun skipWsTokens(): Token {
+        while( current().type in wstokens ) {
+            next()
         }
-        }
-        return default
+        return next()
     }
 
-//    fun expectKeyword(vararg keyword: String): String {
-//        val t = next()
-//        if (t.type != Token.Type.ID && t.value !in keyword) {
-//            throw ScriptError(t.pos, "expected one of ${keyword.joinToString()}")
-//
-//    }
-
-//    data class ReturnScope(val needCatch: Boolean = false)
-
-//    private val
-
-//    fun startReturnScope(): ReturnScope {
-//        return ReturnScope()
-//    }
-
+    companion object {
+        val wstokens = setOf(Token.Type.NEWLINE, Token.Type.MULTILINE_COMMENT, Token.Type.SINLGE_LINE_COMMENT)
+    }
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/ListEntry.kt

@@ -1,5 +1,7 @@
 package net.sergeych.lyng
 
+import net.sergeych.lyng.obj.Accessor
+
 sealed class ListEntry {
     data class Element(val accessor: Accessor) : ListEntry()
 

lynglib/src/commonMain/kotlin/net/sergeych/lyng/LoopBreakContinueException.kt

@@ -1,5 +1,8 @@
 package net.sergeych.lyng
 
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjVoid
+
 class LoopBreakContinueException(
     val doContinue: Boolean,
     val result: Obj = ObjVoid,

lynglib/src/commonMain/kotlin/net/sergeych/lyng/ModuleScope.kt

@@ -0,0 +1,61 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.ObjRecord
+import net.sergeych.lyng.obj.ObjString
+import net.sergeych.lyng.pacman.ImportProvider
+
+/**
+ * Module scope supports importing and contains the [importProvider]; it should be the same
+ * used in [Compiler];
+ */
+class ModuleScope(
+    var importProvider: ImportProvider,
+    pos: Pos = Pos.builtIn,
+    override val packageName: String
+) : Scope(importProvider.rootScope, Arguments.EMPTY, pos) {
+
+    constructor(importProvider: ImportProvider, source: Source) : this(importProvider, source.startPos, source.fileName)
+
+    /**
+     * Import symbols into the scope. It _is called_ after the module is imported by [ImportProvider.prepareImport]
+     * which checks symbol availability and accessibility prior to execution.
+     * @param scope where to copy symbols from this module
+     * @param symbols symbols to import, ir present, only symbols keys will be imported renamed to corresponding values
+     */
+    override suspend fun importInto(scope: Scope, symbols: Map<String, String>?) {
+        val symbolsToImport = symbols?.keys?.toMutableSet()
+        for ((symbol, record) in this.objects) {
+            if (record.visibility.isPublic) {
+                val newName = symbols?.let { ss: Map<String, String> ->
+                    ss[symbol]
+                        ?.also { symbolsToImport!!.remove(it) }
+                        ?: scope.raiseError("internal error: symbol $symbol not found though the module is cached")
+                } ?: symbol
+                val existing = scope.objects[newName]
+                if (existing != null ) {
+                    if (existing.importedFrom != record.importedFrom)
+                        scope.raiseError("symbol ${existing.importedFrom?.packageName}.$newName already exists, redefinition on import is not allowed")
+                    // already imported
+                }
+                else {
+                    // when importing records, we keep track of its package (not otherwise needed)
+                    if (record.importedFrom == null) record.importedFrom = this
+                    scope.objects[newName] = record
+                }
+            }
+        }
+        if (!symbolsToImport.isNullOrEmpty())
+            scope.raiseSymbolNotFound("symbols $packageName.{$symbolsToImport} are.were not found")
+    }
+
+    val packageNameObj by lazy { ObjString(packageName).asReadonly }
+
+    override fun get(name: String): ObjRecord? {
+        return if (name == "__PACKAGE__")
+            packageNameObj
+        else
+            super.get(name)
+    }
+}
+
+

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Parser.kt

@@ -45,12 +45,18 @@ private class Parser(fromPos: Pos) {
             '=' -> {
                 if (pos.currentChar == '=') {
                     pos.advance()
-                    if (currentChar == '=') {
+                    when (currentChar) {
+                        '=' -> {
                             pos.advance()
                             Token("===", from, Token.Type.REF_EQ)
-                    } else
-                        Token("==", from, Token.Type.EQ)
-                } else
+                        }
+                        else -> Token("==", from, Token.Type.EQ)
+                    }
+                } else if( currentChar == '>' ) {
+                    pos.advance()
+                    Token("=>", from, Token.Type.EQARROW)
+                }
+                else
                     Token("=", from, Token.Type.ASSIGN)
             }
 
@@ -103,7 +109,7 @@ private class Parser(fromPos: Pos) {
             '/' -> when (currentChar) {
                 '/' -> {
                     pos.advance()
-                    Token(loadToEnd().trim(), from, Token.Type.SINLGE_LINE_COMMENT)
+                    Token(loadToEndOfLine().trim(), from, Token.Type.SINLGE_LINE_COMMENT)
                 }
 
                 '*' -> {
@@ -137,15 +143,21 @@ private class Parser(fromPos: Pos) {
                 if (currentChar == '.') {
                     pos.advance()
                     // .. already parsed:
-                    if (currentChar == '.') {
+                    when (currentChar) {
+                        '.' -> {
                             pos.advance()
                             Token("...", from, Token.Type.ELLIPSIS)
-                    } else if (currentChar == '<') {
+                        }
+
+                        '<' -> {
                             pos.advance()
                             Token("..<", from, Token.Type.DOTDOTLT)
-                    } else {
+                        }
+
+                        else -> {
                             Token("..", from, Token.Type.DOTDOT)
                         }
+                    }
                 } else
                     Token(".", from, Token.Type.DOT)
             }
@@ -156,8 +168,7 @@ private class Parser(fromPos: Pos) {
                     if (currentChar == '>') {
                         pos.advance()
                         Token("<=>", from, Token.Type.SHUTTLE)
-                    }
-                    else {
+                    } else {
                         Token("<=", from, Token.Type.LTE)
                     }
                 } else
@@ -236,9 +247,10 @@ private class Parser(fromPos: Pos) {
             }
 
             '"' -> loadStringToken()
+
             in digitsSet -> {
                 pos.back()
-                decodeNumber(loadChars(digits), from)
+                decodeNumber(loadChars { it in digitsSet || it == '_'}, from)
             }
 
             '\'' -> {
@@ -261,6 +273,21 @@ private class Parser(fromPos: Pos) {
                 Token(value.toString(), start, Token.Type.CHAR)
             }
 
+            '?' -> {
+                when(currentChar.also { pos.advance() }) {
+                    ':' -> Token("??", from, Token.Type.ELVIS)
+                    '?' -> Token("??", from, Token.Type.ELVIS)
+                    '.' -> Token("?.", from, Token.Type.NULL_COALESCE)
+                    '[' -> Token("?(", from, Token.Type.NULL_COALESCE_INDEX)
+                    '(' -> Token("?(", from, Token.Type.NULL_COALESCE_INVOKE)
+                    '{' -> Token("?{", from, Token.Type.NULL_COALESCE_BLOCKINVOKE)
+                    else -> {
+                        pos.back()
+                        Token("?", from, Token.Type.QUESTION)
+                    }
+                }
+            }
+
             else -> {
                 // text infix operators:
                 // Labels processing is complicated!
@@ -280,8 +307,6 @@ private class Parser(fromPos: Pos) {
                         when (text) {
                             "in" -> Token("in", from, Token.Type.IN)
                             "is" -> Token("is", from, Token.Type.IS)
-                            "protected" -> Token("protected", from, Token.Type.PROTECTED)
-                            "private" -> Token("private", from, Token.Type.PRIVATE)
                             else -> Token(text, from, Token.Type.ID)
                         }
                 } else
@@ -338,7 +363,7 @@ private class Parser(fromPos: Pos) {
             // could be integer, also hex:
             if (currentChar == 'x' && p1 == "0") {
                 pos.advance()
-                Token(loadChars({ it in hexDigits }), start, Token.Type.HEX).also {
+                Token(loadChars { it in hexDigits }, start, Token.Type.HEX).also {
                     if (currentChar.isLetter())
                         raise("invalid hex literal")
                 }
@@ -351,10 +376,11 @@ private class Parser(fromPos: Pos) {
     private val currentChar: Char get() = pos.currentChar
 
     private fun loadStringToken(): Token {
-        var start = currentPos
+        val start = currentPos
 
-        if (currentChar == '"') pos.advance()
-        else start = start.back()
+//        if (currentChar == '"') pos.advance()
+//        else start = start.back()
+//        start = start.back()
 
         val sb = StringBuilder()
         while (currentChar != '"') {
@@ -419,7 +445,7 @@ private class Parser(fromPos: Pos) {
         }
     }
 
-    private fun loadToEnd(): String {
+    private fun loadToEndOfLine(): String {
         val result = StringBuilder()
         val l = pos.line
         do {
@@ -453,4 +479,10 @@ private class Parser(fromPos: Pos) {
         return null
     }
 
+    init {
+        // skip shebang
+        if( pos.readFragment("#!") )
+            loadToEndOfLine()
+    }
+
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Pos.kt

@@ -5,6 +5,7 @@ data class Pos(val source: Source, val line: Int, val column: Int) {
         return "${source.fileName}:${line+1}:${column}"
     }
 
+    @Suppress("unused")
     fun back(): Pos =
         if( column > 0) Pos(source, line, column-1)
         else if( line > 0) Pos(source, line-1, source.lines[line-1].length - 1)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Scope.kt

@@ -0,0 +1,201 @@
+package net.sergeych.lyng
+
+import net.sergeych.lyng.obj.*
+import net.sergeych.lyng.pacman.ImportManager
+import net.sergeych.lyng.pacman.ImportProvider
+
+/**
+ * Scope is where local variables and methods are stored. Scope is also a parent scope for other scopes.
+ * Each block usually creates a scope. Accessing Lyng closures usually is done via a scope.
+ *
+ * To create default scope, use default `Scope()` constructor, it will create a scope with a parent
+ * module scope with default [ImportManager], you can access with [currentImportProvider] as needed.
+ *
+ * If you want to create [ModuleScope] by hand, try [currentImportProvider] and [ImportManager.newModule],
+ * or [ImportManager.newModuleAt].
+ *
+ *  There are special types of scopes:
+ *
+ *  - [AppliedScope] - scope used to apply a closure to some thisObj scope
+ */
+open class Scope(
+    val parent: Scope?,
+    val args: Arguments = Arguments.EMPTY,
+    var pos: Pos = Pos.builtIn,
+    var thisObj: Obj = ObjVoid,
+    var skipScopeCreation: Boolean = false,
+) {
+    open val packageName: String = "<anonymous package>"
+
+    constructor(
+        args: Arguments = Arguments.EMPTY,
+        pos: Pos = Pos.builtIn,
+    )
+            : this(Script.defaultImportManager.copy().newModuleAt(pos), args, pos)
+
+    fun raiseNotImplemented(what: String = "operation"): Nothing = raiseError("$what is not implemented")
+
+    @Suppress("unused")
+    fun raiseNPE(): Nothing = raiseError(ObjNullReferenceException(this))
+
+    @Suppress("unused")
+    fun raiseIndexOutOfBounds(message: String = "Index out of bounds"): Nothing =
+        raiseError(ObjIndexOutOfBoundsException(this, message))
+
+    @Suppress("unused")
+    fun raiseIllegalArgument(message: String = "Illegal argument error"): Nothing =
+        raiseError(ObjIllegalArgumentException(this, message))
+
+    @Suppress("unused")
+    fun raiseIllegalState(message: String = "Illegal argument error"): Nothing =
+        raiseError(ObjIllegalStateException(this, message))
+
+    fun raiseIllegalAssignment(message: String): Nothing =
+        raiseError(ObjIllegalAssignmentException(this, message))
+
+    @Suppress("unused")
+    fun raiseNoSuchElement(message: String = "No such element"): Nothing =
+        raiseError(ObjIllegalArgumentException(this, message))
+
+    fun raiseClassCastError(msg: String): Nothing = raiseError(ObjClassCastException(this, msg))
+
+    @Suppress("unused")
+    fun raiseSymbolNotFound(name: String): Nothing =
+        raiseError(ObjSymbolNotDefinedException(this, "symbol is not defined: $name"))
+
+    fun raiseError(message: String): Nothing {
+        throw ExecutionError(ObjException(this, message))
+    }
+
+    fun raiseError(obj: ObjException): Nothing {
+        throw ExecutionError(obj)
+    }
+
+    inline fun <reified T : Obj> requiredArg(index: Int): T {
+        if (args.list.size <= index) raiseError("Expected at least ${index + 1} argument, got ${args.list.size}")
+        return (args.list[index] as? T)
+            ?: raiseClassCastError("Expected type ${T::class.simpleName}, got ${args.list[index]::class.simpleName}")
+    }
+
+    inline fun <reified T : Obj> requireOnlyArg(): T {
+        if (args.list.size != 1) raiseError("Expected exactly 1 argument, got ${args.list.size}")
+        return requiredArg(0)
+    }
+
+    @Suppress("unused")
+    fun requireExactCount(count: Int) {
+        if (args.list.size != count) {
+            raiseError("Expected exactly $count arguments, got ${args.list.size}")
+        }
+    }
+
+    fun requireNoArgs() {
+        if( args.list.isNotEmpty())
+            raiseError("This function does not accept any arguments")
+    }
+
+    inline fun <reified T : Obj> thisAs(): T = (thisObj as? T)
+        ?: raiseClassCastError("Cannot cast ${thisObj.objClass.className} to ${T::class.simpleName}")
+
+    internal val objects = mutableMapOf<String, ObjRecord>()
+
+    open operator fun get(name: String): ObjRecord? =
+        if (name == "this") thisObj.asReadonly
+        else {
+            objects[name]
+                ?: parent?.get(name)
+                ?: thisObj.objClass.getInstanceMemberOrNull(name)
+        }
+
+    fun copy(pos: Pos, args: Arguments = Arguments.EMPTY, newThisObj: Obj? = null): Scope =
+        Scope(this, args, pos, newThisObj ?: thisObj)
+
+    fun copy(args: Arguments = Arguments.EMPTY, newThisObj: Obj? = null): Scope =
+        Scope(this, args, pos, newThisObj ?: thisObj)
+
+    fun copy() = Scope(this, args, pos, thisObj)
+
+    fun addItem(
+        name: String,
+        isMutable: Boolean,
+        value: Obj,
+        visibility: Visibility = Visibility.Public,
+        recordType: ObjRecord.Type = ObjRecord.Type.Other
+    ): ObjRecord {
+        return ObjRecord(value, isMutable, visibility,type = recordType).also { objects[name] = it }
+    }
+
+    fun getOrCreateNamespace(name: String): ObjClass {
+        val ns = objects.getOrPut(name) { ObjRecord(ObjNamespace(name), isMutable = false) }.value
+        return ns.objClass
+    }
+
+    inline fun addVoidFn(vararg names: String, crossinline fn: suspend Scope.() -> Unit) {
+        addFn<ObjVoid>(*names) {
+            fn(this)
+            ObjVoid
+        }
+    }
+
+    inline fun <reified T : Obj> addFn(vararg names: String, crossinline fn: suspend Scope.() -> T) {
+        val newFn = object : Statement() {
+            override val pos: Pos = Pos.builtIn
+
+            override suspend fun execute(scope: Scope): Obj = scope.fn()
+
+        }
+        for (name in names) {
+            addItem(
+                name,
+                false,
+                newFn
+            )
+        }
+    }
+
+    fun addConst(name: String, value: Obj) = addItem(name, false, value)
+
+    suspend fun eval(code: String): Obj =
+        Compiler.compile(code.toSource(), currentImportProvider).execute(this)
+
+    suspend fun eval(source: Source): Obj =
+        Compiler.compile(
+            source,
+            currentImportProvider
+        ).execute(this)
+
+    fun containsLocal(name: String): Boolean = name in objects
+
+    /**
+     * Some scopes can be imported into other scopes, like [ModuleScope]. Those must correctly implement this method.
+     * @param scope where to copy symbols from this module
+     * @param symbols symbols to import, ir present, only symbols keys will be imported renamed to corresponding values
+     */
+    open suspend fun importInto(scope: Scope, symbols: Map<String, String>? = null) {
+        scope.raiseError(ObjIllegalOperationException(scope, "Import is not allowed here: import $packageName"))
+    }
+
+    /**
+     * Find a first [ImportManager] in this Scope hierarchy. Normally there should be one. Found instance is cached.
+     *
+     * Use it to register your package sources, see [ImportManager] features.
+     *
+     * @throws IllegalStateException if there is no such manager (if you create some specific scope with no manager,
+     *      then you knew what you did)
+     */
+    val currentImportProvider: ImportProvider by lazy {
+        if (this is ModuleScope)
+            importProvider.getActualProvider()
+        else
+            parent?.currentImportProvider ?: throw IllegalStateException("this scope has no manager in the chain")
+    }
+
+    val importManager by lazy { (currentImportProvider as? ImportManager)
+        ?: throw IllegalStateException("this scope has no manager in the chain (provided $currentImportProvider") }
+
+    companion object {
+
+        fun new(): Scope =
+            Script.defaultImportManager.copy().newModuleAt(Pos.builtIn)
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Script.kt

@@ -1,6 +1,9 @@
 package net.sergeych.lyng
 
 import kotlinx.coroutines.delay
+import net.sergeych.lyng.obj.*
+import net.sergeych.lyng.pacman.ImportManager
+import net.sergeych.lynon.ObjLynonClass
 import kotlin.math.*
 
 class Script(
@@ -9,18 +12,19 @@ class Script(
 //    private val catchReturn: Boolean = false,
 ) : Statement() {
 
-    override suspend fun execute(context: Context): Obj {
+    override suspend fun execute(scope: Scope): Obj {
         var lastResult: Obj = ObjVoid
         for (s in statements) {
-            lastResult = s.execute(context)
+            lastResult = s.execute(scope)
         }
         return lastResult
     }
 
-    suspend fun execute() = execute(defaultContext.copy(pos = pos))
+    suspend fun execute() = execute(defaultImportManager.newModule())
 
     companion object {
-        val defaultContext: Context = Context().apply {
+
+        private val rootScope: Scope = Scope(null).apply {
             ObjException.addExceptionsToContext(this)
             addFn("println") {
                 for ((i, a) in args.withIndex()) {
@@ -127,6 +131,12 @@ class Script(
                 if( a.compareTo(this, b) != 0 )
                     raiseError(ObjAssertionFailedException(this,"Assertion failed: ${a.inspect()} == ${b.inspect()}"))
             }
+            addVoidFn("assertNotEquals") {
+                val a = requiredArg<Obj>(0)
+                val b = requiredArg<Obj>(1)
+                if( a.compareTo(this, b) == 0 )
+                    raiseError(ObjAssertionFailedException(this,"Assertion failed: ${a.inspect()} != ${b.inspect()}"))
+            }
             addFn("assertThrows") {
                 val code = requireOnlyArg<Statement>()
                 val result =try {
@@ -146,20 +156,24 @@ class Script(
                 delay((this.args.firstAndOnly().toDouble()/1000.0).roundToLong())
             }
 
+            addConst("Object", rootObjectType)
             addConst("Real", ObjReal.type)
             addConst("String", ObjString.type)
             addConst("Int", ObjInt.type)
             addConst("Bool", ObjBool.type)
             addConst("Char", ObjChar.type)
             addConst("List", ObjList.type)
+            addConst("Set", ObjSet.type)
             addConst("Range", ObjRange.type)
+            addConst("Map", ObjMap.type)
+            addConst("MapEntry", ObjMapEntry.type)
             @Suppress("RemoveRedundantQualifierName")
             addConst("Callable", Statement.type)
             // interfaces
             addConst("Iterable", ObjIterable)
+            addConst("Collection", ObjCollection)
             addConst("Array", ObjArray)
             addConst("Class", ObjClassType)
-            addConst("Object", Obj().objClass)
 
             val pi = ObjReal(PI)
             addConst("π", pi)
@@ -167,5 +181,33 @@ class Script(
                 addConst("PI", pi)
             }
         }
+
+        val defaultImportManager: ImportManager by lazy {
+            ImportManager(rootScope, SecurityManager.allowAll).apply {
+                addPackage("lyng.buffer") {
+                    it.addConst("Buffer", ObjBuffer.type)
+                    it.addConst("MutableBuffer", ObjMutableBuffer.type)
+                }
+                addPackage("lyng.serialization") {
+                    it.addConst("Lynon", ObjLynonClass)
+                }
+                addPackage("lyng.time") {
+                    it.addConst("Instant", ObjInstant.type)
+                    it.addConst("Duration", ObjDuration.type)
+                    it.addFn("delay") {
+                        val a = args.firstAndOnly()
+                        when(a) {
+                            is ObjInt -> delay(a.value * 1000)
+                            is ObjReal -> delay((a.value * 1000).roundToLong())
+                            is ObjDuration -> delay(a.duration)
+                            else -> raiseIllegalArgument("Expected Duration, Int or Real, got ${a.inspect()}")
+                        }
+                        ObjVoid
+                    }
+                }
+            }
+
+        }
+
     }
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/ScriptError.kt

@@ -2,6 +2,8 @@
 
 package net.sergeych.lyng
 
+import net.sergeych.lyng.obj.ObjException
+
 open class ScriptError(val pos: Pos, val errorMessage: String, cause: Throwable? = null) : Exception(
     """
         $pos: Error: $errorMessage
@@ -12,4 +14,6 @@ open class ScriptError(val pos: Pos, val errorMessage: String,cause: Throwable?=
     cause
 )
 
-class ExecutionError(val errorObject: ObjException) : ScriptError(errorObject.context.pos, errorObject.message)
+class ExecutionError(val errorObject: ObjException) : ScriptError(errorObject.scope.pos, errorObject.message)
+
+class ImportException(pos: Pos, message: String) : ScriptError(pos, message)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/SecurityManager.kt

@@ -0,0 +1,22 @@
+package net.sergeych.lyng
+
+interface SecurityManager {
+    /**
+     * Check that any symbol from the corresponding module can be imported. If it returns false,
+     * the module will not be imported and no further processing will be done
+     */
+    fun canImportModule(name: String): Boolean
+
+    /**\
+     * if [canImportModule] this method allows fine-grained control over symbols.
+     */
+    fun canImportSymbol(moduleName: String, symbolName: String): Boolean = true
+
+    companion object {
+        val allowAll: SecurityManager = object : SecurityManager {
+            override fun canImportModule(name: String): Boolean = true
+            override fun canImportSymbol(moduleName: String, symbolName: String): Boolean = true
+        }
+    }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Source.kt

@@ -0,0 +1,26 @@
+package net.sergeych.lyng
+
+class Source(val fileName: String, text: String) {
+
+    val lines = text.lines().map { it.trimEnd() }
+
+    companion object {
+        val builtIn: Source by lazy { Source("built-in", "") }
+        val UNKNOWN: Source by lazy { Source("UNKNOWN", "") }
+    }
+
+    val startPos: Pos = Pos(this, 0, 0)
+
+    fun posAt(line: Int, column: Int): Pos = Pos(this, line, column)
+
+    fun extractPackageName(): String {
+        for ((n,line) in lines.withIndex()) {
+            if( line.isBlank() || line.isEmpty() )
+                continue
+            if( line.startsWith("package ") )
+                return line.substring(8).trim()
+            else throw ScriptError(Pos(this, n, 0),"package declaration expected")
+        }
+        throw ScriptError(Pos(this, 0, 0),"package declaration expected")
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Token.kt

@@ -14,14 +14,18 @@ data class Token(val value: String, val pos: Pos, val type: Type) {
         IN, NOTIN, IS, NOTIS,
         EQ, NEQ, LT, LTE, GT, GTE, REF_EQ, REF_NEQ,
         SHUTTLE,
-        AND, BITAND, OR, BITOR, NOT, BITNOT, DOT, ARROW, QUESTION, COLONCOLON,
+        AND, BITAND, OR, BITOR, NOT, BITNOT, DOT, ARROW, EQARROW, QUESTION, COLONCOLON,
         SINLGE_LINE_COMMENT, MULTILINE_COMMENT,
         LABEL, ATLABEL, // label@ at@label
-        PRIVATE, PROTECTED,
         //PUBLIC, PROTECTED, INTERNAL, EXPORT, OPEN, INLINE, OVERRIDE, ABSTRACT, SEALED, EXTERNAL, VAL, VAR, CONST, TYPE, FUN, CLASS, INTERFACE, ENUM, OBJECT, TRAIT, THIS,
         ELLIPSIS, DOTDOT, DOTDOTLT,
         NEWLINE,
         EOF,
+        NULL_COALESCE,
+        ELVIS,
+        NULL_COALESCE_INDEX,
+        NULL_COALESCE_INVOKE,
+        NULL_COALESCE_BLOCKINVOKE,
     }
 
     companion object {

lynglib/src/commonMain/kotlin/net/sergeych/lyng/TypeDecl.kt

@@ -0,0 +1,14 @@
+@file:Suppress("unused")
+
+package net.sergeych.lyng
+
+// this is highly experimental and subject to complete redesign
+// very soon
+sealed class TypeDecl(val isNullable:Boolean = false) {
+    // ??
+//    data class Fn(val argTypes: List<ArgsDeclaration.Item>, val retType: TypeDecl) : TypeDecl()
+    object TypeAny : TypeDecl()
+    object TypeNullableAny : TypeDecl(true)
+
+    class Simple(val name: String,isNullable: Boolean) : TypeDecl(isNullable)
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Accessor.kt

@@ -0,0 +1,33 @@
+
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Compiler
+import net.sergeych.lyng.Pos
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.ScriptError
+
+// avoid KDOC bug: keep it
+@Suppress("unused")
+typealias DocCompiler = Compiler
+/**
+ * When we need read-write access to an object in some abstract storage, we need Accessor,
+ * as in-site assigning is not always sufficient, in general case we need to replace the object
+ * in the storage.
+ *
+ * Note that assigning new value is more complex than just replacing the object, see how assignment
+ * operator is implemented in [Compiler.allOps].
+ */
+data class Accessor(
+    val getter: suspend (Scope) -> ObjRecord,
+    val setterOrNull: (suspend (Scope, Obj) -> Unit)?
+) {
+    /**
+     * Simplified constructor for immutable stores.
+     */
+    constructor(getter: suspend (Scope) -> ObjRecord) : this(getter, null)
+
+    /**
+     * Get the setter or throw.
+     */
+    fun setter(pos: Pos) = setterOrNull ?: throw ScriptError(pos, "can't assign value")
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/Obj.kt

@@ -0,0 +1,546 @@
+package net.sergeych.lyng.obj
+
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import net.sergeych.bintools.encodeToHex
+import net.sergeych.lyng.*
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+import net.sergeych.synctools.ProtectedOp
+import net.sergeych.synctools.withLock
+import kotlin.contracts.ExperimentalContracts
+
+open class Obj {
+
+    open val isConst: Boolean = false
+
+    fun ensureNotConst(scope: Scope) {
+        if (isConst) scope.raiseError("can't assign to constant")
+    }
+
+    val isNull by lazy { this === ObjNull }
+
+    var isFrozen: Boolean = false
+
+    private val monitor = Mutex()
+
+    //    private val memberMutex = Mutex()
+    internal var parentInstances: MutableList<Obj> = mutableListOf()
+
+    private val opInstances = ProtectedOp()
+
+    open fun inspect(): String = toString()
+
+    /**
+     * Some objects are by-value, historically [ObjInt] and [ObjReal] are usually treated as such.
+     * When initializing a var with it, by value objects must be copied. By-reference ones aren't.
+     *
+     * Almost all objects are by-reference.
+     */
+    open fun byValueCopy(): Obj = this
+
+    @Suppress("SuspiciousEqualsCombination")
+    fun isInstanceOf(someClass: Obj) = someClass === objClass ||
+            objClass.allParentsSet.contains(someClass) ||
+            someClass == rootObjectType
+
+
+    suspend fun invokeInstanceMethod(scope: Scope, name: String, vararg args: Obj): Obj =
+        invokeInstanceMethod(scope, name, Arguments(args.toList()))
+
+    suspend inline fun <reified T : Obj> callMethod(
+        scope: Scope,
+        name: String,
+        args: Arguments = Arguments.EMPTY
+    ): T = invokeInstanceMethod(scope, name, args) as T
+
+    /**
+     * Invoke a method of the object if exists
+     * it [onNotFoundResult] is not null, it returns it when symbol is not found
+     * otherwise throws [ObjSymbolNotDefinedException] object exception
+     */
+    open suspend fun invokeInstanceMethod(
+        scope: Scope,
+        name: String,
+        args: Arguments = Arguments.EMPTY,
+        onNotFoundResult: Obj?=null
+    ): Obj =
+        objClass.getInstanceMemberOrNull(name)?.value?.invoke(scope, this, args)
+            ?: onNotFoundResult
+            ?: scope.raiseSymbolNotFound(name)
+
+    open suspend fun getInstanceMethod(
+        scope: Scope,
+        name: String,
+        args: Arguments = Arguments.EMPTY
+    ): Obj =
+        // note that getInstanceMember traverses the hierarchy
+        objClass.getInstanceMember(scope.pos, name).value
+
+    fun getMemberOrNull(name: String): Obj? = objClass.getInstanceMemberOrNull(name)?.value
+
+    // methods that to override
+
+    open suspend fun compareTo(scope: Scope, other: Obj): Int {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun contains(scope: Scope, other: Obj): Boolean {
+        return invokeInstanceMethod(scope, "contains", other).toBool()
+    }
+
+    open val asStr: ObjString by lazy {
+        if (this is ObjString) this else ObjString(this.toString())
+    }
+
+    /**
+     * Class of the object: definition of member functions (top-level), etc.
+     * Note that using lazy allows to avoid endless recursion here
+     */
+    open val objClass: ObjClass = rootObjectType
+
+    open suspend fun plus(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun minus(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun negate(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun mul(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun div(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun mod(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun logicalNot(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun logicalAnd(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun logicalOr(scope: Scope, other: Obj): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun assign(scope: Scope, other: Obj): Obj? = null
+
+    /**
+     * a += b
+     * if( the operation is not defined, it returns null and the compiler would try
+     * to generate it as 'this = this + other', reassigning its variable
+     */
+    open suspend fun plusAssign(scope: Scope, other: Obj): Obj? = null
+
+    /**
+     * `-=` operations, see [plusAssign]
+     */
+    open suspend fun minusAssign(scope: Scope, other: Obj): Obj? = null
+    open suspend fun mulAssign(scope: Scope, other: Obj): Obj? = null
+    open suspend fun divAssign(scope: Scope, other: Obj): Obj? = null
+    open suspend fun modAssign(scope: Scope, other: Obj): Obj? = null
+
+    open suspend fun getAndIncrement(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun incrementAndGet(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun decrementAndGet(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    open suspend fun getAndDecrement(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    /**
+     * Convert Lyng object to its Kotlin counterpart
+     */
+    open suspend fun toKotlin(scope: Scope): Any? {
+        return toString()
+    }
+
+    fun willMutate(scope: Scope) {
+        if (isFrozen) scope.raiseError("attempt to mutate frozen object")
+    }
+
+    suspend fun <T> sync(block: () -> T): T = monitor.withLock { block() }
+
+    open suspend fun readField(scope: Scope, name: String): ObjRecord {
+        // could be property or class field:
+        val obj = objClass.getInstanceMemberOrNull(name) ?: scope.raiseError("no such field: $name")
+        return when (val value = obj.value) {
+            is Statement -> {
+                ObjRecord(value.execute(scope.copy(scope.pos, newThisObj = this)), obj.isMutable)
+            }
+            // could be writable property naturally
+//            null -> ObjNull.asReadonly
+            else -> obj
+        }
+    }
+
+    open suspend fun writeField(scope: Scope, name: String, newValue: Obj) {
+        willMutate(scope)
+        val field = objClass.getInstanceMemberOrNull(name) ?: scope.raiseError("no such field: $name")
+        if (field.isMutable) field.value = newValue else scope.raiseError("can't assign to read-only field: $name")
+    }
+
+    open suspend fun getAt(scope: Scope, index: Obj): Obj {
+        scope.raiseNotImplemented("indexing")
+    }
+
+    suspend fun getAt(scope: Scope, index: Int): Obj = getAt(scope, ObjInt(index.toLong()))
+
+    open suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
+        scope.raiseNotImplemented("indexing")
+    }
+
+    open suspend fun callOn(scope: Scope): Obj {
+        scope.raiseNotImplemented()
+    }
+
+    suspend fun invoke(scope: Scope, thisObj: Obj, args: Arguments): Obj =
+        callOn(scope.copy(scope.pos, args = args, newThisObj = thisObj))
+
+    suspend fun invoke(scope: Scope, thisObj: Obj, vararg args: Obj): Obj =
+        callOn(
+            scope.copy(
+                scope.pos,
+                args = Arguments(args.toList()),
+                newThisObj = thisObj
+            )
+        )
+
+    suspend fun invoke(scope: Scope, thisObj: Obj): Obj =
+        callOn(
+            scope.copy(
+                scope.pos,
+                args = Arguments.EMPTY,
+                newThisObj = thisObj
+            )
+        )
+
+    suspend fun invoke(scope: Scope, atPos: Pos, thisObj: Obj, args: Arguments): Obj =
+        callOn(scope.copy(atPos, args = args, newThisObj = thisObj))
+
+
+    val asReadonly: ObjRecord by lazy { ObjRecord(this, false) }
+    val asMutable: ObjRecord by lazy { ObjRecord(this, true) }
+
+    open suspend fun lynonType(): LynonType = LynonType.Other
+
+    open suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        scope.raiseNotImplemented()
+    }
+
+    companion object {
+
+        val rootObjectType = ObjClass("Obj").apply {
+            addFn("toString") {
+                thisObj.asStr
+            }
+            addFn("contains") {
+                ObjBool(thisObj.contains(this, args.firstAndOnly()))
+            }
+            // utilities
+            addFn("let") {
+                args.firstAndOnly().callOn(copy(Arguments(thisObj)))
+            }
+            addFn("apply") {
+                val newContext = (thisObj as? ObjInstance)?.instanceScope ?: this
+                args.firstAndOnly()
+                    .callOn(newContext)
+                thisObj
+            }
+            addFn("also") {
+                args.firstAndOnly().callOn(copy(Arguments(thisObj)))
+                thisObj
+            }
+            addFn("getAt") {
+                requireExactCount(1)
+                thisObj.getAt(this, requiredArg<Obj>(0))
+            }
+            addFn("putAt") {
+                requireExactCount(2)
+                val newValue = args[1]
+                thisObj.putAt(this, requiredArg<Obj>(0), newValue)
+                newValue
+            }
+
+        }
+
+
+        inline fun from(obj: Any?): Obj {
+            @Suppress("UNCHECKED_CAST")
+            return when (obj) {
+                is Obj -> obj
+                is Double -> ObjReal(obj)
+                is Float -> ObjReal(obj.toDouble())
+                is Int -> ObjInt(obj.toLong())
+                is Long -> ObjInt(obj)
+                is String -> ObjString(obj)
+                is CharSequence -> ObjString(obj.toString())
+                is Boolean -> ObjBool(obj)
+                is Set<*> -> ObjSet((obj as Set<Obj>).toMutableSet())
+                Unit -> ObjVoid
+                null -> ObjNull
+                is Iterator<*> -> ObjKotlinIterator(obj)
+                is Map.Entry<*, *> -> {
+                    obj as MutableMap.MutableEntry<Obj, Obj>
+                    ObjMapEntry(obj.key, obj.value)
+                }
+
+                else -> throw IllegalArgumentException("cannot convert to Obj: $obj")
+            }
+        }
+    }
+}
+
+fun Double.toObj(): Obj = ObjReal(this)
+
+@Suppress("unused")
+inline fun <reified T> T.toObj(): Obj = Obj.from(this)
+
+@Serializable
+@SerialName("void")
+object ObjVoid : Obj() {
+    override fun equals(other: Any?): Boolean {
+        return other is ObjVoid || other is Unit
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        return if (other === this) 0 else -1
+    }
+
+    override fun toString(): String = "void"
+}
+
+@Serializable
+@SerialName("null")
+object ObjNull : Obj() {
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        return if (other === this) 0 else -1
+    }
+
+    override fun equals(other: Any?): Boolean {
+        return other is ObjNull || other == null
+    }
+
+    override suspend fun readField(scope: Scope, name: String): ObjRecord {
+        scope.raiseNPE()
+    }
+
+    override suspend fun invokeInstanceMethod(scope: Scope, name: String, args: Arguments, onNotFoundResult: Obj?): Obj {
+        scope.raiseNPE()
+    }
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj {
+        scope.raiseNPE()
+    }
+
+    override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
+        scope.raiseNPE()
+    }
+
+    override suspend fun callOn(scope: Scope): Obj {
+        scope.raiseNPE()
+    }
+
+    override fun toString(): String = "null"
+
+    override suspend fun toKotlin(scope: Scope): Any? {
+        return null
+    }
+
+    override suspend fun lynonType(): LynonType {
+        return LynonType.Null
+    }
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        if (lynonType == null) {
+            encoder.putBit(0)
+        }
+    }
+
+    override val objClass: ObjClass by lazy {
+        object : ObjClass("Null") {
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj {
+                if (lynonType == LynonType.Null)
+                    return this@ObjNull
+                else
+                    scope.raiseIllegalState("can't deserialize null directly or with wrong type: ${lynonType}")
+            }
+        }
+    }
+}
+
+interface Numeric {
+    val longValue: Long
+    val doubleValue: Double
+    val toObjInt: ObjInt
+    val toObjReal: ObjReal
+}
+
+fun Obj.toDouble(): Double =
+    (this as? Numeric)?.doubleValue
+        ?: (this as? ObjString)?.value?.toDouble()
+        ?: throw IllegalArgumentException("cannot convert to double $this")
+
+@Suppress("unused")
+fun Obj.toLong(): Long =
+    when (this) {
+        is Numeric -> longValue
+        is ObjString -> value.toLong()
+        is ObjChar -> value.code.toLong()
+        else -> throw IllegalArgumentException("cannot convert to double $this")
+    }
+
+fun Obj.toInt(): Int = toLong().toInt()
+
+fun Obj.toBool(): Boolean =
+    (this as? ObjBool)?.value ?: throw IllegalArgumentException("cannot convert to boolean $this")
+
+
+data class ObjNamespace(val name: String) : Obj() {
+    override val objClass by lazy { ObjClass(name) }
+
+    override fun inspect(): String = "Ns[$name]"
+
+    override fun toString(): String {
+        return "package $name"
+    }
+}
+
+open class ObjException(exceptionClass: ExceptionClass, val scope: Scope, val message: String) : Obj() {
+    constructor(name: String, scope: Scope, message: String) : this(
+        getOrCreateExceptionClass(name),
+        scope,
+        message
+    )
+
+    constructor(scope: Scope, message: String) : this(Root, scope, message)
+
+    fun raise(): Nothing {
+        throw ExecutionError(this)
+    }
+
+    override val objClass: ObjClass = exceptionClass
+
+    override fun toString(): String {
+        return "ObjException:${objClass.className}:${scope.pos}@${hashCode().encodeToHex()}"
+    }
+
+    companion object {
+
+        class ExceptionClass(val name: String, vararg parents: ObjClass) : ObjClass(name, *parents) {
+            override suspend fun callOn(scope: Scope): Obj {
+                val message = scope.args.getOrNull(0)?.toString() ?: name
+                return ObjException(this, scope, message)
+            }
+
+            override fun toString(): String = "ExceptionClass[$name]@${hashCode().encodeToHex()}"
+        }
+
+        val Root = ExceptionClass("Throwable").apply {
+            addConst("message", statement {
+                (thisObj as ObjException).message.toObj()
+            })
+        }
+
+        private val op = ProtectedOp()
+        private val existingErrorClasses = mutableMapOf<String, ExceptionClass>()
+
+
+        @OptIn(ExperimentalContracts::class)
+        protected fun getOrCreateExceptionClass(name: String): ExceptionClass {
+            return op.withLock {
+                existingErrorClasses.getOrPut(name) {
+                    ExceptionClass(name, Root)
+                }
+            }
+        }
+
+        /**
+         * Get [ObjClass] for error class by name if exists.
+         */
+        @OptIn(ExperimentalContracts::class)
+        fun getErrorClass(name: String): ObjClass? = op.withLock {
+            existingErrorClasses[name]
+        }
+
+        fun addExceptionsToContext(scope: Scope) {
+            scope.addConst("Exception", Root)
+            existingErrorClasses["Exception"] = Root
+            for (name in listOf(
+                "NullReferenceException",
+                "AssertionFailedException",
+                "ClassCastException",
+                "IndexOutOfBoundsException",
+                "IllegalArgumentException",
+                "NoSuchElementException",
+                "IllegalAssignmentException",
+                "SymbolNotDefinedException",
+                "IterationEndException",
+                "AccessException",
+                "UnknownException",
+            )) {
+                scope.addConst(name, getOrCreateExceptionClass(name))
+            }
+        }
+    }
+}
+
+class ObjNullReferenceException(scope: Scope) : ObjException("NullReferenceException", scope, "object is null")
+
+class ObjAssertionFailedException(scope: Scope, message: String) :
+    ObjException("AssertionFailedException", scope, message)
+
+class ObjClassCastException(scope: Scope, message: String) : ObjException("ClassCastException", scope, message)
+class ObjIndexOutOfBoundsException(scope: Scope, message: String = "index out of bounds") :
+    ObjException("IndexOutOfBoundsException", scope, message)
+
+class ObjIllegalArgumentException(scope: Scope, message: String = "illegal argument") :
+    ObjException("IllegalArgumentException", scope, message)
+
+class ObjIllegalStateException(scope: Scope, message: String = "illegal state") :
+    ObjException("IllegalStateException", scope, message)
+
+@Suppress("unused")
+class ObjNoSuchElementException(scope: Scope, message: String = "no such element") :
+    ObjException("IllegalArgumentException", scope, message)
+
+class ObjIllegalAssignmentException(scope: Scope, message: String = "illegal assignment") :
+    ObjException("NoSuchElementException", scope, message)
+
+class ObjSymbolNotDefinedException(scope: Scope, message: String = "symbol is not defined") :
+    ObjException("SymbolNotDefinedException", scope, message)
+
+class ObjIterationFinishedException(scope: Scope) :
+    ObjException("IterationEndException", scope, "iteration finished")
+
+class ObjAccessException(scope: Scope, message: String = "access not allowed error") :
+    ObjException("AccessException", scope, message)
+
+class ObjUnknownException(scope: Scope, message: String = "access not allowed error") :
+    ObjException("UnknownException", scope, message)
+
+class ObjIllegalOperationException(scope: Scope, message: String = "Operation is illegal") :
+    ObjException("IllegalOperationException", scope, message)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjArray.kt

@@ -0,0 +1,38 @@
+package net.sergeych.lyng.obj
+
+val ObjArray by lazy {
+
+    /**
+     * Array abstract class is a [ObjCollection] with `getAt` method.
+     */
+    ObjClass("Array", ObjCollection).apply {
+        // we can create iterators using size/getat:
+
+        addFn("iterator") {
+            ObjArrayIterator(thisObj).also { it.init(this) }
+        }
+
+        addFn("contains", isOpen = true) {
+            val obj = args.firstAndOnly()
+            for (i in 0..<thisObj.invokeInstanceMethod(this, "size").toInt()) {
+                if (thisObj.getAt(this, ObjInt(i.toLong())).compareTo(this, obj) == 0) return@addFn ObjTrue
+            }
+            ObjFalse
+        }
+
+        addFn("last") {
+            thisObj.invokeInstanceMethod(
+                this,
+                "getAt",
+                (thisObj.invokeInstanceMethod(this, "size").toInt() - 1).toObj()
+            )
+        }
+
+        addFn("lastIndex") { (thisObj.invokeInstanceMethod(this, "size").toInt() - 1).toObj() }
+
+        addFn("indices") {
+            ObjRange(0.toObj(), thisObj.invokeInstanceMethod(this, "size"), false)
+        }
+
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjArrayIterator.kt

@@ -0,0 +1,34 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+
+class ObjArrayIterator(val array: Obj) : Obj() {
+
+    override val objClass: ObjClass by lazy { type }
+
+    private var nextIndex = 0
+    private var lastIndex = 0
+
+    suspend fun init(scope: Scope) {
+        nextIndex = 0
+        lastIndex = array.invokeInstanceMethod(scope, "size").toInt()
+        ObjVoid
+    }
+
+    companion object {
+        val type by lazy {
+            ObjClass("ArrayIterator", ObjIterator).apply {
+                addFn("next") {
+                    val self = thisAs<ObjArrayIterator>()
+                    if (self.nextIndex < self.lastIndex) {
+                        self.array.invokeInstanceMethod(this, "getAt", (self.nextIndex++).toObj())
+                    } else raiseError(ObjIterationFinishedException(this))
+                }
+                addFn("hasNext") {
+                    val self = thisAs<ObjArrayIterator>()
+                    if (self.nextIndex < self.lastIndex) ObjTrue else ObjFalse
+                }
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjBitBuffer.kt

@@ -0,0 +1,37 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.bintools.toDump
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.BitArray
+
+class ObjBitBuffer(val bitArray: BitArray) : Obj() {
+
+    override val objClass = type
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj {
+        return bitArray[index.toLong()].toObj()
+    }
+
+    companion object {
+        val type = object: ObjClass("BitBuffer", ObjArray) {
+
+        }.apply {
+            addFn("toBuffer") {
+                requireNoArgs()
+                ObjBuffer(thisAs<ObjBitBuffer>().bitArray.asUbyteArray())
+            }
+            addFn("toDump") {
+                requireNoArgs()
+                ObjString(
+                    thisAs<ObjBitBuffer>().bitArray.asUbyteArray().toDump()
+                )
+            }
+            addFn("size") {
+                thisAs<ObjBitBuffer>().bitArray.size.toObj()
+            }
+            addFn("sizeInBytes") {
+                ObjInt((thisAs<ObjBitBuffer>().bitArray.size + 7) shr 3)
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjBool.kt

@@ -0,0 +1,59 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+
+data class ObjBool(val value: Boolean) : Obj() {
+    override val asStr by lazy { ObjString(value.toString()) }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is ObjBool) return -2
+        return value.compareTo(other.value)
+    }
+
+    override fun hashCode(): Int {
+        return value.hashCode()
+    }
+
+    override fun toString(): String = value.toString()
+
+    override val objClass: ObjClass = type
+
+    override suspend fun logicalNot(scope: Scope): Obj = ObjBool(!value)
+
+    override suspend fun logicalAnd(scope: Scope, other: Obj): Obj = ObjBool(value && other.toBool())
+
+    override suspend fun logicalOr(scope: Scope, other: Obj): Obj = ObjBool(value || other.toBool())
+
+    override suspend fun toKotlin(scope: Scope): Any {
+        return value
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.Bool
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeBoolean(value)
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjBool
+
+        return value == other.value
+    }
+
+    companion object {
+        val type = object : ObjClass("Bool") {
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder,lynonType: LynonType?): Obj {
+                return ObjBool(decoder.unpackBoolean())
+            }
+        }
+    }
+}
+
+val ObjTrue = ObjBool(true)
+val ObjFalse = ObjBool(false)

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjBuffer.kt

@@ -0,0 +1,166 @@
+package net.sergeych.lyng.obj
+
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.toList
+import net.sergeych.bintools.encodeToHex
+import net.sergeych.bintools.toDump
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.statement
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+import kotlin.math.min
+
+open class ObjBuffer(val byteArray: UByteArray) : Obj() {
+
+    override val objClass: ObjClass = type
+
+    fun checkIndex(scope: Scope, index: Obj): Int {
+        if (index !is ObjInt)
+            scope.raiseIllegalArgument("index must be Int")
+        val i = index.value.toInt()
+        if (i < 0) scope.raiseIllegalArgument("index must be positive")
+        if (i >= byteArray.size)
+            scope.raiseIndexOutOfBounds("index $i is out of bounds 0..<${byteArray.size}")
+        return i
+    }
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj {
+        // notice: we create a copy if content, so we don't want it
+        // to be treated as modifiable, or putAt will not be called:
+        return if (index is ObjRange) {
+            val start: Int = index.startInt(scope)
+            val end: Int = index.exclusiveIntEnd(scope) ?: size
+            ObjBuffer(byteArray.sliceArray(start..<end))
+        } else ObjInt(byteArray[checkIndex(scope, index)].toLong(), true)
+    }
+
+    val size by byteArray::size
+
+    override fun hashCode(): Int {
+        return byteArray.hashCode()
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is ObjBuffer) return super.compareTo(scope, other)
+        val limit = min(size, other.size)
+        for (i in 0..<limit) {
+            val own = byteArray[i]
+            val their = other.byteArray[i]
+            if (own < their) return -1
+            else if (own > their) return 1
+        }
+        if (size < other.size) return -1
+        if (size > other.size) return 1
+        return 0
+    }
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj {
+        return if (other is ObjBuffer)
+            ObjBuffer(byteArray + other.byteArray)
+        else if (other.isInstanceOf(ObjIterable)) {
+            ObjBuffer(
+                byteArray + other.toFlow(scope).map { it.toLong().toUByte() }.toList().toTypedArray()
+                    .toUByteArray()
+            )
+        } else scope.raiseIllegalArgument("can't concatenate buffer with ${other.inspect()}")
+    }
+
+    override fun toString(): String {
+        return "Buffer(${byteArray.encodeToHex()})"
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjBuffer
+
+        return byteArray contentEquals other.byteArray
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.Buffer
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeCachedBytes(byteArray.asByteArray())
+    }
+
+    companion object {
+        private suspend fun createBufferFrom(scope: Scope, obj: Obj): ObjBuffer =
+            when (obj) {
+                is ObjBuffer -> ObjBuffer(obj.byteArray.copyOf())
+                is ObjInt -> {
+                    if (obj.value < 0)
+                        scope.raiseIllegalArgument("buffer size must be positive")
+                    val data = UByteArray(obj.value.toInt())
+                    ObjBuffer(data)
+                }
+
+                is ObjString -> ObjBuffer(obj.value.encodeToByteArray().asUByteArray())
+                else -> {
+                    if (obj.isInstanceOf(ObjIterable)) {
+                        ObjBuffer(
+                            obj.toFlow(scope).map { it.toLong().toUByte() }.toList().toTypedArray()
+                                .toUByteArray()
+                        )
+                    } else
+                        scope.raiseIllegalArgument(
+                            "can't construct buffer from ${obj.inspect()}"
+                        )
+                }
+            }
+
+        val type = object : ObjClass("Buffer", ObjArray) {
+            override suspend fun callOn(scope: Scope): Obj {
+                val args = scope.args.list
+                return when (args.size) {
+                    // empty buffer
+                    0 -> ObjBuffer(ubyteArrayOf())
+                    1 -> createBufferFrom(scope, args[0])
+                    else -> {
+                        // create buffer from array, each argument should be a byte then:
+                        val data = UByteArray(args.size)
+                        for ((i, b) in args.withIndex()) {
+                            val code = when (b) {
+                                is ObjChar -> b.value.code.toUByte()
+                                is ObjInt -> b.value.toUByte()
+                                else -> scope.raiseIllegalArgument(
+                                    "invalid byte value for buffer constructor at index $i: ${b.inspect()}"
+                                )
+                            }
+                            data[i] = code
+                        }
+                        ObjBuffer(data)
+                    }
+                }
+            }
+
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj =
+                ObjBuffer( decoder.decodeCached {
+                    decoder.decompress().asUByteArray()
+                })
+
+        }.apply {
+            createField("size",
+                statement {
+                    (thisObj as ObjBuffer).byteArray.size.toObj()
+                }
+            )
+            addFn("decodeUtf8") {
+                ObjString(
+                    thisAs<ObjBuffer>().byteArray.toByteArray().decodeToString()
+                )
+            }
+            addFn("toMutable") {
+                requireNoArgs()
+                ObjMutableBuffer(thisAs<ObjBuffer>().byteArray.copyOf())
+            }
+            addFn("toDump") {
+                requireNoArgs()
+                ObjString(
+                    thisAs<ObjBuffer>().byteArray.toByteArray().toDump()
+                )
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjChar.kt

@@ -0,0 +1,34 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+
+class ObjChar(val value: Char): Obj() {
+
+    override val objClass: ObjClass = type
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int =
+        (other as? ObjChar)?.let { value.compareTo(it.value) } ?: -1
+
+    override fun toString(): String = value.toString()
+
+    override fun inspect(): String = "'$value'"
+
+    override fun hashCode(): Int {
+        return value.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjChar
+
+        return value == other.value
+    }
+
+    companion object {
+        val type = ObjClass("Char").apply {
+            addFn("code") { ObjInt(thisAs<ObjChar>().value.code.toLong()) }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjClass.kt

@@ -0,0 +1,136 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.*
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonType
+
+val ObjClassType by lazy { ObjClass("Class") }
+
+open class ObjClass(
+    val className: String,
+    vararg parents: ObjClass,
+) : Obj() {
+
+    val classNameObj by lazy { ObjString(className) }
+
+    var constructorMeta: ArgsDeclaration? = null
+    var instanceConstructor: Statement? = null
+
+    /**
+     * the scope for class methods, initialize class vars, etc.
+     *
+     * Important notice. When create a user class, e.g. from Lyng source, it should
+     * be set to a scope by compiler, so it could access local closure, etc. Otherwise,
+     * it will be initialized to default scope on first necessity, e.g. when used in
+     * external, kotlin classes with [addClassConst] and [addClassFn], etc.
+     */
+    var classScope: Scope? = null
+
+    val allParentsSet: Set<ObjClass> =
+        parents.flatMap {
+            listOf(it) + it.allParentsSet
+        }.toMutableSet()
+
+    override val objClass: ObjClass by lazy { ObjClassType }
+
+    /**
+     * members: fields most often. These are called with [ObjInstance] withs ths [ObjInstance.objClass]
+     */
+    private val members = mutableMapOf<String, ObjRecord>()
+
+    override fun toString(): String = className
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int = if (other === this) 0 else -1
+
+    override suspend fun callOn(scope: Scope): Obj {
+        val instance = ObjInstance(this)
+        instance.instanceScope = scope.copy(newThisObj = instance,args = scope.args)
+        if (instanceConstructor != null) {
+            instanceConstructor!!.execute(instance.instanceScope)
+        }
+        return instance
+    }
+
+
+    fun createField(
+        name: String,
+        initialValue: Obj,
+        isMutable: Boolean = false,
+        visibility: Visibility = Visibility.Public,
+        pos: Pos = Pos.builtIn
+    ) {
+        val existing = members[name] ?: allParentsSet.firstNotNullOfOrNull { it.members[name] }
+        if( existing?.isMutable == false)
+            throw ScriptError(pos, "$name is already defined in $objClass or one of its supertypes")
+        members[name] = ObjRecord(initialValue, isMutable, visibility)
+    }
+
+    private fun initClassScope(): Scope {
+        if( classScope == null ) classScope = Scope()
+        return classScope!!
+    }
+
+    fun createClassField(
+        name: String,
+        initialValue: Obj,
+        isMutable: Boolean = false,
+        visibility: Visibility = Visibility.Public,
+        pos: Pos = Pos.builtIn
+    ) {
+        initClassScope()
+        val existing = classScope!!.objects[name]
+        if( existing != null)
+            throw ScriptError(pos, "$name is already defined in $objClass or one of its supertypes")
+        classScope!!.addItem(name, isMutable, initialValue, visibility)
+    }
+
+    fun addFn(name: String, isOpen: Boolean = false, code: suspend Scope.() -> Obj) {
+        createField(name, statement { code() }, isOpen)
+    }
+
+    fun addConst(name: String, value: Obj) = createField(name, value, isMutable = false)
+    fun addClassConst(name: String, value: Obj) = createClassField(name, value)
+    fun addClassFn(name: String, isOpen: Boolean = false, code: suspend Scope.() -> Obj) {
+        createClassField(name, statement { code() }, isOpen)
+    }
+
+
+    /**
+     * Get instance member traversing the hierarchy if needed. Its meaning is different for different objects.
+     */
+    fun getInstanceMemberOrNull(name: String): ObjRecord? {
+        members[name]?.let { return it }
+        allParentsSet.forEach { parent -> parent.getInstanceMemberOrNull(name)?.let { return it } }
+        return rootObjectType.members[name]
+    }
+
+    fun getInstanceMember(atPos: Pos, name: String): ObjRecord =
+        getInstanceMemberOrNull(name)
+            ?: throw ScriptError(atPos, "symbol doesn't exist: $name")
+
+    override suspend fun readField(scope: Scope, name: String): ObjRecord {
+        classScope?.objects?.get(name)?.let {
+            if( it.visibility.isPublic ) return it
+        }
+        return super.readField(scope, name)
+    }
+
+    override suspend fun writeField(scope: Scope, name: String, newValue: Obj) {
+        initClassScope().objects[name]?.let {
+            if( it.isMutable) it.value = newValue
+            else scope.raiseIllegalAssignment("can't assign $name is not mutable")
+        }
+            ?: super.writeField(scope, name, newValue)
+    }
+
+    override suspend fun invokeInstanceMethod(scope: Scope, name: String, args: Arguments,
+                                              onNotFoundResult: Obj?): Obj {
+        return classScope?.objects?.get(name)?.value?.invoke(scope, this, args)
+            ?: super.invokeInstanceMethod(scope, name, args, onNotFoundResult)
+    }
+
+    open suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj = scope.raiseNotImplemented()
+
+}
+
+

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjCollection.kt

@@ -0,0 +1,8 @@
+package net.sergeych.lyng.obj
+
+/**
+ * Collection is an iterator with `size`]
+ */
+val ObjCollection = ObjClass("Collection", ObjIterable).apply {
+
+    }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjDuration.kt

@@ -0,0 +1,154 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.days
+import kotlin.time.Duration.Companion.hours
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.DurationUnit
+
+class ObjDuration(val duration: Duration) : Obj() {
+    override val objClass: ObjClass = type
+
+    override fun toString(): String {
+        return duration.toString()
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        return if( other is ObjDuration)
+            duration.compareTo(other.duration)
+        else -1
+    }
+
+    override fun hashCode(): Int {
+        return duration.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjDuration
+
+        return duration == other.duration
+    }
+
+    companion object {
+        val type = object : ObjClass("Duration") {
+            override suspend fun callOn(scope: Scope): Obj {
+                val args = scope.args
+                if( args.list.size > 1 )
+                    scope.raiseIllegalArgument("can't construct Duration(${args.inspect()})")
+                val a0 = args.list.getOrNull(0)
+
+                return ObjDuration(
+                    when (a0) {
+                        null -> Duration.ZERO
+                        is ObjInt -> a0.value.seconds
+                        is ObjReal -> a0.value.seconds
+                        else -> {
+                            scope.raiseIllegalArgument("can't construct Instant(${args.inspect()})")
+                        }
+                    }
+                )
+            }
+        }.apply {
+            addFn("days") {
+                thisAs<ObjDuration>().duration.toDouble(DurationUnit.DAYS).toObj()
+            }
+            addFn("hours") {
+                thisAs<ObjDuration>().duration.toDouble(DurationUnit.HOURS).toObj()
+            }
+            addFn("minutes") {
+                thisAs<ObjDuration>().duration.toDouble(DurationUnit.MINUTES).toObj()
+            }
+            addFn("seconds") {
+                thisAs<ObjDuration>().duration.toDouble(DurationUnit.SECONDS).toObj()
+            }
+            addFn("milliseconds") {
+                thisAs<ObjDuration>().duration.toDouble(DurationUnit.MILLISECONDS).toObj()
+            }
+            addFn("microseconds") {
+                thisAs<ObjDuration>().duration.toDouble(DurationUnit.MICROSECONDS).toObj()
+            }
+            // extensions
+
+            ObjInt.type.addFn("seconds") {
+                ObjDuration(thisAs<ObjInt>().value.seconds)
+            }
+
+            ObjInt.type.addFn("second") {
+                ObjDuration(thisAs<ObjInt>().value.seconds)
+            }
+            ObjInt.type.addFn("milliseconds") {
+                ObjDuration(thisAs<ObjInt>().value.milliseconds)
+            }
+
+            ObjInt.type.addFn("millisecond") {
+                ObjDuration(thisAs<ObjInt>().value.milliseconds)
+            }
+            ObjReal.type.addFn("seconds") {
+                ObjDuration(thisAs<ObjReal>().value.seconds)
+            }
+
+            ObjReal.type.addFn("second") {
+                ObjDuration(thisAs<ObjReal>().value.seconds)
+            }
+
+            ObjReal.type.addFn("milliseconds") {
+                ObjDuration(thisAs<ObjReal>().value.milliseconds)
+            }
+            ObjReal.type.addFn("millisecond") {
+                ObjDuration(thisAs<ObjReal>().value.milliseconds)
+            }
+
+            ObjInt.type.addFn("minutes") {
+                ObjDuration(thisAs<ObjInt>().value.minutes)
+            }
+            ObjReal.type.addFn("minutes") {
+                ObjDuration(thisAs<ObjReal>().value.minutes)
+            }
+            ObjInt.type.addFn("minute") {
+                ObjDuration(thisAs<ObjInt>().value.minutes)
+            }
+            ObjReal.type.addFn("minute") {
+                ObjDuration(thisAs<ObjReal>().value.minutes)
+            }
+            ObjInt.type.addFn("hours") {
+                ObjDuration(thisAs<ObjInt>().value.hours)
+            }
+            ObjReal.type.addFn("hours") {
+                ObjDuration(thisAs<ObjReal>().value.hours)
+            }
+            ObjInt.type.addFn("hour") {
+                ObjDuration(thisAs<ObjInt>().value.hours)
+            }
+            ObjReal.type.addFn("hour") {
+                ObjDuration(thisAs<ObjReal>().value.hours)
+            }
+            ObjInt.type.addFn("days") {
+                ObjDuration(thisAs<ObjInt>().value.days)
+            }
+            ObjReal.type.addFn("days") {
+                ObjDuration(thisAs<ObjReal>().value.days)
+            }
+            ObjInt.type.addFn("day") {
+                ObjDuration(thisAs<ObjInt>().value.days)
+            }
+            ObjReal.type.addFn("day") {
+                ObjDuration(thisAs<ObjReal>().value.days)
+            }
+
+
+//            addFn("epochSeconds") {
+//                val instant = thisAs<ObjInstant>().instant
+//                ObjReal(instant.epochSeconds + instant.nanosecondsOfSecond * 1e-9)
+//            }
+//            addFn("epochMilliseconds") {
+//                ObjInt(instant.toEpochMilliseconds())
+//            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstance.kt

@@ -0,0 +1,106 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+
+class ObjInstance(override val objClass: ObjClass) : Obj() {
+
+    internal lateinit var instanceScope: Scope
+
+    override suspend fun readField(scope: Scope, name: String): ObjRecord {
+        return instanceScope[name]?.let {
+            if (it.visibility.isPublic)
+                it
+            else
+                scope.raiseError(ObjAccessException(scope, "can't access non-public field $name"))
+        }
+            ?: super.readField(scope, name)
+    }
+
+    override suspend fun writeField(scope: Scope, name: String, newValue: Obj) {
+        instanceScope[name]?.let { f ->
+            if (!f.visibility.isPublic)
+                ObjIllegalAssignmentException(scope, "can't assign to non-public field $name")
+            if (!f.isMutable) ObjIllegalAssignmentException(scope, "can't reassign val $name").raise()
+            if (f.value.assign(scope, newValue) == null)
+                f.value = newValue
+        } ?: super.writeField(scope, name, newValue)
+    }
+
+    override suspend fun invokeInstanceMethod(scope: Scope, name: String, args: Arguments,
+                                              onNotFoundResult: Obj?): Obj =
+        instanceScope[name]?.let {
+            if (it.visibility.isPublic)
+                it.value.invoke(scope, this, args)
+            else
+                scope.raiseError(ObjAccessException(scope, "can't invoke non-public method $name"))
+        }
+            ?: super.invokeInstanceMethod(scope, name, args, onNotFoundResult)
+
+    private val publicFields: Map<String, ObjRecord>
+        get() = instanceScope.objects.filter { it.value.visibility.isPublic }
+
+    override fun toString(): String {
+        val fields = publicFields.map { "${it.key}=${it.value.value}" }.joinToString(",")
+        return "${objClass.className}($fields)"
+    }
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        val meta = objClass.constructorMeta
+            ?: scope.raiseError("can't serialize non-serializable object (no constructor meta)")
+        // actual constructor can vary, for example, adding new fields with default
+        // values, so we save size of the construction:
+
+        // using objlist allow for some optimizations:
+        val params = meta.params.map { readField(scope, it.name).value }
+        encoder.encodeAnyList(scope, params)
+        serializeStateVars(scope, encoder)
+    }
+
+    protected val instanceVars: Map<String, ObjRecord> by lazy {
+        instanceScope.objects.filter { it.value.type.serializable }
+    }
+
+    protected suspend fun serializeStateVars(scope: Scope,encoder: LynonEncoder) {
+        val vars = instanceVars.values.map { it.value }
+        if( vars.isNotEmpty()) {
+            encoder.encodeAnyList(scope, vars)
+            println("serialized state vars $vars")
+        }
+    }
+
+    internal suspend fun deserializeStateVars(scope: Scope, decoder: LynonDecoder) {
+        val localVars = instanceVars.values.toList()
+        if( localVars.isNotEmpty() ) {
+            println("gonna read vars")
+            val vars = decoder.decodeAnyList(scope)
+            if (vars.size > instanceVars.size)
+                scope.raiseIllegalArgument("serialized vars has bigger size than instance vars")
+            println("deser state vars $vars")
+            for ((i, v) in vars.withIndex()) {
+                localVars[i].value = v
+            }
+        }
+    }
+
+    protected val comparableVars: Map<String, ObjRecord> by lazy {
+        instanceScope.objects.filter {
+            it.value.type.comparable
+        }
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is ObjInstance) return -1
+        if (other.objClass != objClass) return -1
+        for (f in comparableVars) {
+            val a = f.value.value
+            val b = other.instanceScope[f.key]!!.value
+            val d = a.compareTo(scope, b)
+            if (d != 0) return d
+        }
+        return 0
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstanceClass.kt

@@ -0,0 +1,26 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonType
+
+/**
+ * Special variant of [ObjClass] to be used in [ObjInstance], e.g. for Lyng compiled classes
+ */
+class ObjInstanceClass(val name: String) : ObjClass(name) {
+
+    override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj {
+        val args = decoder.decodeAnyList(scope)
+        println("deserializing constructor $name, $args params")
+        val actualSize = constructorMeta?.params?.size ?: 0
+        if( args.size > actualSize )
+            scope.raiseIllegalArgument("constructor $name has only $actualSize but serialized version has ${args.size}")
+        val newScope = scope.copy(args = Arguments(args))
+        return (callOn(newScope) as ObjInstance).apply {
+            deserializeStateVars(scope,decoder)
+            invokeInstanceMethod(scope, "onDeserialized", onNotFoundResult = ObjVoid)
+        }
+    }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInstant.kt

@@ -0,0 +1,178 @@
+package net.sergeych.lyng.obj
+
+import kotlinx.datetime.Clock
+import kotlinx.datetime.Instant
+import kotlinx.datetime.isDistantFuture
+import kotlinx.datetime.isDistantPast
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonSettings
+import net.sergeych.lynon.LynonType
+
+class ObjInstant(val instant: Instant,val truncateMode: LynonSettings.InstantTruncateMode=LynonSettings.InstantTruncateMode.Microsecond) : Obj() {
+    override val objClass: ObjClass get() = type
+
+    override fun toString(): String {
+        return instant.toString()
+    }
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj {
+        return when (other) {
+            is ObjDuration -> ObjInstant(instant + other.duration)
+            else -> super.plus(scope, other)
+        }
+    }
+
+    override suspend fun minus(scope: Scope, other: Obj): Obj {
+        return when (other) {
+            is ObjDuration -> ObjInstant(instant - other.duration)
+            is ObjInstant -> ObjDuration(instant - other.instant)
+            else -> super.plus(scope, other)
+        }
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if( other is ObjInstant) {
+            return instant.compareTo(other.instant)
+        }
+        return super.compareTo(scope, other)
+    }
+
+    override suspend fun toKotlin(scope: Scope): Any {
+        return instant
+    }
+
+    override fun hashCode(): Int {
+        return instant.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjInstant
+
+        return instant == other.instant
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.Instant
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.putBits(truncateMode.ordinal, 2)
+        when(truncateMode) {
+            LynonSettings.InstantTruncateMode.Millisecond ->
+                encoder.encodeSigned(instant.toEpochMilliseconds())
+            LynonSettings.InstantTruncateMode.Second ->
+                encoder.encodeSigned(instant.epochSeconds)
+            LynonSettings.InstantTruncateMode.Microsecond -> {
+                encoder.encodeSigned(instant.epochSeconds)
+                encoder.encodeUnsigned(instant.nanosecondsOfSecond.toULong() / 1000UL)
+            }
+        }
+    }
+
+    companion object {
+        val distantFuture by lazy {
+            ObjInstant(Instant.DISTANT_FUTURE)
+        }
+
+        val distantPast by lazy {
+            ObjInstant(Instant.DISTANT_PAST)
+        }
+
+        val type = object : ObjClass("Instant") {
+            override suspend fun callOn(scope: Scope): Obj {
+                val args = scope.args
+                val a0 = args.list.getOrNull(0)
+                return ObjInstant(
+                    when (a0) {
+                        null -> {
+                            val t = Clock.System.now()
+                            Instant.fromEpochSeconds(t.epochSeconds, t.nanosecondsOfSecond)
+                        }
+                        is ObjInt -> Instant.fromEpochSeconds(a0.value)
+                        is ObjReal -> {
+                            val seconds = a0.value.toLong()
+                            val nanos = (a0.value - seconds) * 1e9
+                            Instant.fromEpochSeconds(seconds, nanos.toLong())
+                        }
+                        is ObjInstant -> a0.instant
+
+                        else -> {
+                            scope.raiseIllegalArgument("can't construct Instant(${args.inspect()})")
+                        }
+                    }
+                )
+            }
+
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj {
+                val mode = LynonSettings.InstantTruncateMode.entries[decoder.getBitsAsInt(2)]
+                return when (mode) {
+                    LynonSettings.InstantTruncateMode.Microsecond -> ObjInstant(
+                        Instant.fromEpochSeconds(
+                            decoder.unpackSigned(), decoder.unpackUnsignedInt() * 1000
+                        )
+                    )
+                    LynonSettings.InstantTruncateMode.Millisecond -> ObjInstant(
+                        Instant.fromEpochMilliseconds(
+                            decoder.unpackSigned()
+                        )
+                    )
+                    LynonSettings.InstantTruncateMode.Second -> ObjInstant(
+                        Instant.fromEpochSeconds(decoder.unpackSigned())
+                    )
+                }
+            }
+
+        }.apply {
+            addFn("epochSeconds") {
+                val instant = thisAs<ObjInstant>().instant
+                ObjReal(instant.epochSeconds + instant.nanosecondsOfSecond * 1e-9)
+            }
+            addFn("isDistantFuture") {
+                thisAs<ObjInstant>().instant.isDistantFuture.toObj()
+            }
+            addFn("isDistantPast") {
+                thisAs<ObjInstant>().instant.isDistantPast.toObj()
+            }
+            addFn("epochWholeSeconds") {
+                ObjInt(thisAs<ObjInstant>().instant.epochSeconds)
+            }
+            addFn("nanosecondsOfSecond") {
+                ObjInt(thisAs<ObjInstant>().instant.nanosecondsOfSecond.toLong())
+            }
+            addFn("truncateToSecond") {
+                val t = thisAs<ObjInstant>().instant
+                ObjInstant(Instant.fromEpochSeconds(t.epochSeconds), LynonSettings.InstantTruncateMode.Second)
+            }
+            addFn("truncateToMillisecond") {
+                val t = thisAs<ObjInstant>().instant
+                ObjInstant(
+                    Instant.fromEpochSeconds(t.epochSeconds, t.nanosecondsOfSecond / 1_000_000 * 1_000_000),
+                    LynonSettings.InstantTruncateMode.Millisecond
+                )
+            }
+            addFn("truncateToMicrosecond") {
+                val t = thisAs<ObjInstant>().instant
+                ObjInstant(
+                    Instant.fromEpochSeconds(t.epochSeconds, t.nanosecondsOfSecond / 1_000 * 1_000),
+                    LynonSettings.InstantTruncateMode.Microsecond
+                )
+            }
+            // class members
+
+            addClassConst("distantFuture", distantFuture)
+            addClassConst("distantPast", distantPast)
+            addClassFn("now") {
+                ObjInstant(Clock.System.now())
+            }
+//            addFn("epochMilliseconds") {
+//                ObjInt(instant.toEpochMilliseconds())
+//            }
+        }
+
+    }
+}
+
+

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjInt.kt

@@ -0,0 +1,142 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+
+class ObjInt(var value: Long, override val isConst: Boolean = false) : Obj(), Numeric {
+    override val asStr get() = ObjString(value.toString())
+    override val longValue get() = value
+    override val doubleValue get() = value.toDouble()
+    override val toObjInt get() = this
+    override val toObjReal = ObjReal(doubleValue)
+
+    override fun byValueCopy(): Obj = ObjInt(value)
+
+    override fun hashCode(): Int {
+        return value.hashCode()
+    }
+
+    override suspend fun getAndIncrement(scope: Scope): Obj {
+        ensureNotConst(scope)
+        return ObjInt(value).also { value++ }
+    }
+
+    override suspend fun getAndDecrement(scope: Scope): Obj {
+        ensureNotConst(scope)
+        return ObjInt(value).also { value-- }
+    }
+
+    override suspend fun incrementAndGet(scope: Scope): Obj {
+        ensureNotConst(scope)
+        return ObjInt(++value)
+    }
+
+    override suspend fun decrementAndGet(scope: Scope): Obj {
+        ensureNotConst(scope)
+        return ObjInt(--value)
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is Numeric) return -2
+        return value.compareTo(other.doubleValue)
+    }
+
+    override fun toString(): String = value.toString()
+
+    override val objClass: ObjClass = type
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj =
+        if (other is ObjInt)
+            ObjInt(this.value + other.value)
+        else
+            ObjReal(this.doubleValue + other.toDouble())
+
+    override suspend fun minus(scope: Scope, other: Obj): Obj =
+        if (other is ObjInt)
+            ObjInt(this.value - other.value)
+        else
+            ObjReal(this.doubleValue - other.toDouble())
+
+    override suspend fun mul(scope: Scope, other: Obj): Obj =
+        if (other is ObjInt) {
+            ObjInt(this.value * other.value)
+        } else ObjReal(this.value * other.toDouble())
+
+    override suspend fun div(scope: Scope, other: Obj): Obj =
+        if (other is ObjInt)
+            ObjInt(this.value / other.value)
+        else ObjReal(this.value / other.toDouble())
+
+    override suspend fun mod(scope: Scope, other: Obj): Obj =
+        if (other is ObjInt)
+            ObjInt(this.value % other.value)
+        else ObjReal(this.value.toDouble() % other.toDouble())
+
+    /**
+     * We are by-value type ([byValueCopy] is implemented) so we can do in-place
+     * assignment
+     */
+    override suspend fun assign(scope: Scope, other: Obj): Obj? {
+        return if (!isConst && other is ObjInt) {
+            value = other.value
+            this
+        } else null
+    }
+
+    override suspend fun toKotlin(scope: Scope): Any {
+        return value
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjInt
+
+        return value == other.value
+    }
+
+    override suspend fun negate(scope: Scope): Obj {
+        return ObjInt(-value)
+    }
+
+    override suspend fun lynonType(): LynonType = when (value) {
+        0L -> LynonType.Int0
+        else -> {
+            if (value > 0) LynonType.IntPositive
+            else LynonType.IntNegative
+        }
+    }
+
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        when (lynonType) {
+            null -> encoder.encodeSigned(value)
+            LynonType.Int0 -> {}
+            LynonType.IntPositive -> encoder.encodeUnsigned(value.toULong())
+            LynonType.IntNegative -> encoder.encodeUnsigned((-value).toULong())
+            LynonType.IntSigned -> encoder.encodeSigned(value)
+            else -> scope.raiseIllegalArgument("Unsupported lynon type code for Int: $lynonType")
+        }
+    }
+
+    companion object {
+        val Zero = ObjInt(0, true)
+        val One = ObjInt(1, true)
+        val type = object : ObjClass("Int") {
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj =
+                when (lynonType) {
+                    null -> ObjInt(decoder.unpackSigned())
+                    LynonType.Int0 -> Zero
+                    LynonType.IntPositive -> ObjInt(decoder.unpackUnsigned().toLong())
+                    LynonType.IntNegative -> ObjInt(-decoder.unpackUnsigned().toLong())
+                    LynonType.IntSigned -> ObjInt(decoder.unpackSigned())
+                    else -> scope.raiseIllegalState("illegal type code for Int: $lynonType")
+                }
+        }
+    }
+}
+
+fun Int.toObj() = ObjInt(this.toLong())

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjIterable.kt

@@ -0,0 +1,98 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.Statement
+
+/**
+ * Abstract class that must provide `iterator` method that returns [ObjIterator] instance.
+ */
+val ObjIterable by lazy {
+    ObjClass("Iterable").apply {
+
+        addFn("toList") {
+            val result = mutableListOf<Obj>()
+            val iterator = thisObj.invokeInstanceMethod(this, "iterator")
+
+            while (iterator.invokeInstanceMethod(this, "hasNext").toBool())
+                result += iterator.invokeInstanceMethod(this, "next")
+            ObjList(result)
+        }
+
+        // it is not effective, but it is open:
+        addFn("contains", isOpen = true) {
+            val obj = args.firstAndOnly()
+            val it = thisObj.invokeInstanceMethod(this, "iterator")
+            while (it.invokeInstanceMethod(this, "hasNext").toBool()) {
+                if (obj.compareTo(this, it.invokeInstanceMethod(this, "next")) == 0)
+                    return@addFn ObjTrue
+            }
+            ObjFalse
+        }
+
+        addFn("indexOf", isOpen = true) {
+            val obj = args.firstAndOnly()
+            var index = 0
+            val it = thisObj.invokeInstanceMethod(this, "iterator")
+            while (it.invokeInstanceMethod(this, "hasNext").toBool()) {
+                if (obj.compareTo(this, it.invokeInstanceMethod(this, "next")) == 0)
+                    return@addFn ObjInt(index.toLong())
+                index++
+            }
+            ObjInt(-1L)
+        }
+
+        addFn("toSet") {
+            val result = mutableSetOf<Obj>()
+            val it = thisObj.invokeInstanceMethod(this, "iterator")
+            while (it.invokeInstanceMethod(this, "hasNext").toBool()) {
+                result += it.invokeInstanceMethod(this, "next")
+            }
+            ObjSet(result)
+        }
+
+        addFn("toMap") {
+            val result = ObjMap()
+            thisObj.toFlow(this).collect { pair ->
+                result.map[pair.getAt(this,0)] = pair.getAt(this, 1)
+            }
+            result
+        }
+
+        addFn("associateBy") {
+            val association = requireOnlyArg<Statement>()
+            val result = ObjMap()
+            thisObj.toFlow(this).collect {
+                result.map[association.call(this, it)] = it
+            }
+            result
+        }
+
+        addFn("forEach", isOpen = true) {
+            val it = thisObj.invokeInstanceMethod(this, "iterator")
+            val fn = requiredArg<Statement>(0)
+            while (it.invokeInstanceMethod(this, "hasNext").toBool()) {
+                val x = it.invokeInstanceMethod(this, "next")
+                fn.execute(this.copy(Arguments(listOf(x))))
+            }
+            ObjVoid
+        }
+
+        addFn("map", isOpen = true) {
+            val fn = requiredArg<Statement>(0)
+            val result = mutableListOf<Obj>()
+            thisObj.toFlow(this).collect {
+                result += fn.call(this, it)
+            }
+            ObjList(result)
+        }
+
+        addFn("isEmpty") {
+            ObjBool(
+                thisObj.invokeInstanceMethod(this, "iterator")
+                    .invokeInstanceMethod(this, "hasNext").toBool()
+                    .not()
+            )
+        }
+
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjIterator.kt

@@ -0,0 +1,3 @@
+package net.sergeych.lyng.obj
+
+val ObjIterator by lazy { ObjClass("Iterator") }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjKotlinIterator.kt

@@ -0,0 +1,58 @@
+@file:Suppress("unused")
+
+package net.sergeych.lyng.obj
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import net.sergeych.lyng.Scope
+
+/**
+ * Iterator wrapper to allow Kotlin collections to be returned from Lyng objects;
+ * each object is converted to a Lyng object.
+ */
+class ObjKotlinIterator(val iterator: Iterator<Any?>) : Obj() {
+
+    override val objClass = type
+
+    companion object {
+        val type = ObjClass("KotlinIterator", ObjIterator).apply {
+            addFn("next") { thisAs<ObjKotlinIterator>().iterator.next().toObj() }
+            addFn("hasNext") { thisAs<ObjKotlinIterator>().iterator.hasNext().toObj() }
+        }
+
+    }
+}
+
+/**
+ * Propagate kotlin iterator that already produces Lyng objects, no conversion
+ * is applied
+ */
+class ObjKotlinObjIterator(val iterator: Iterator<Obj>) : Obj() {
+
+    override val objClass = type
+
+    companion object {
+        val type = ObjClass("KotlinIterator", ObjIterator).apply {
+            addFn("next") {
+                thisAs<ObjKotlinObjIterator>().iterator.next()
+            }
+            addFn("hasNext") { thisAs<ObjKotlinIterator>().iterator.hasNext().toObj() }
+        }
+
+    }
+}
+
+/**
+ * Convert Lyng's Iterable to Kotlin's Flow.
+ *
+ * As Lyng is totally asynchronous, its iterator can't be trivially converted to Kotlin's synchronous iterator.
+ * It is, though, trivially convertible to Kotlin's Flow.
+ */
+fun Obj.toFlow(scope: Scope): Flow<Obj> = flow {
+    val iterator = invokeInstanceMethod(scope, "iterator")
+    val hasNext = iterator.getInstanceMethod(scope, "hasNext")
+    val next = iterator.getInstanceMethod(scope, "next")
+    while (hasNext.invoke(scope, iterator).toBool()) {
+        emit(next.invoke(scope, iterator))
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjList.kt

@@ -0,0 +1,229 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.statement
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+
+class ObjList(val list: MutableList<Obj> = mutableListOf()) : Obj() {
+
+    override fun toString(): String = "[${
+        list.joinToString(separator = ", ") { it.inspect() }
+    }]"
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj {
+        return when (index) {
+            is ObjInt -> {
+                list[index.toInt()]
+            }
+
+            is ObjRange -> {
+                when {
+                    index.start is ObjInt && index.end is ObjInt -> {
+                        if (index.isEndInclusive)
+                            ObjList(list.subList(index.start.toInt(), index.end.toInt() + 1).toMutableList())
+                        else
+                            ObjList(list.subList(index.start.toInt(), index.end.toInt()).toMutableList())
+                    }
+
+                    index.isOpenStart && !index.isOpenEnd -> {
+                        if (index.isEndInclusive)
+                            ObjList(list.subList(0, index.end!!.toInt() + 1).toMutableList())
+                        else
+                            ObjList(list.subList(0, index.end!!.toInt()).toMutableList())
+                    }
+
+                    index.isOpenEnd && !index.isOpenStart -> {
+                        ObjList(list.subList(index.start!!.toInt(), list.size).toMutableList())
+                    }
+
+                    index.isOpenStart && index.isOpenEnd -> {
+                        ObjList(list.toMutableList())
+                    }
+
+                    else -> {
+                        throw RuntimeException("Can't apply range for index: $index")
+                    }
+                }
+            }
+
+            else -> scope.raiseIllegalArgument("Illegal index object for a list: ${index.inspect()}")
+        }
+    }
+
+    override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
+        list[index.toInt()] = newValue
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is ObjList) return -2
+        val mySize = list.size
+        val otherSize = other.list.size
+        val commonSize = minOf(mySize, otherSize)
+        for (i in 0..<commonSize) {
+            if (list[i].compareTo(scope, other.list[i]) != 0) {
+                return list[i].compareTo(scope, other.list[i])
+            }
+        }
+        // equal so far, longer is greater:
+        return when {
+            mySize < otherSize -> -1
+            mySize > otherSize -> 1
+            else -> 0
+        }
+    }
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj =
+        when {
+            other is ObjList ->
+                ObjList((list + other.list).toMutableList())
+
+            other.isInstanceOf(ObjIterable) -> {
+                val l = other.callMethod<ObjList>(scope, "toList")
+                ObjList((list + l.list).toMutableList())
+            }
+
+            else ->
+                scope.raiseError("'+': can't concatenate $this with $other")
+        }
+
+
+    override suspend fun plusAssign(scope: Scope, other: Obj): Obj {
+        // optimization
+        if (other is ObjList) {
+            list += other.list
+            return this
+        }
+        if (other.isInstanceOf(ObjIterable)) {
+            val otherList = other.invokeInstanceMethod(scope, "toList") as ObjList
+            list += otherList.list
+        } else
+            list += other
+        return this
+    }
+
+    override suspend fun contains(scope: Scope, other: Obj): Boolean {
+        return list.contains(other)
+    }
+
+    override val objClass: ObjClass
+        get() = type
+
+    override suspend fun toKotlin(scope: Scope): Any {
+        return list.map { it.toKotlin(scope) }
+    }
+
+    override fun hashCode(): Int {
+        // check?
+        return list.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjList
+
+        return list == other.list
+    }
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeAnyList(scope,list)
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.List
+
+    companion object {
+        val type = object : ObjClass("List", ObjArray) {
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj {
+                return ObjList(decoder.decodeAnyList(scope))
+            }
+        }.apply {
+            createField("size",
+                statement {
+                    (thisObj as ObjList).list.size.toObj()
+                }
+            )
+            createField("add",
+                statement {
+                    val l = thisAs<ObjList>().list
+                    for (a in args) l.add(a)
+                    ObjVoid
+                }
+            )
+            addFn("insertAt") {
+                if (args.size < 2) raiseError("addAt takes 2+ arguments")
+                val l = thisAs<ObjList>()
+                var index = requiredArg<ObjInt>(0).value.toInt()
+                for (i in 1..<args.size) l.list.add(index++, args[i])
+                ObjVoid
+            }
+
+            addFn("removeAt") {
+                val self = thisAs<ObjList>()
+                val start = requiredArg<ObjInt>(0).value.toInt()
+                if (args.size == 2) {
+                    val end = requireOnlyArg<ObjInt>().value.toInt()
+                    self.list.subList(start, end).clear()
+                } else
+                    self.list.removeAt(start)
+                self
+            }
+
+            addFn("removeLast") {
+                val self = thisAs<ObjList>()
+                if (args.isNotEmpty()) {
+                    val count = requireOnlyArg<ObjInt>().value.toInt()
+                    val size = self.list.size
+                    if (count >= size) self.list.clear()
+                    else self.list.subList(size - count, size).clear()
+                } else self.list.removeLast()
+                self
+            }
+
+            addFn("removeRange") {
+                val self = thisAs<ObjList>()
+                val list = self.list
+                val range = requiredArg<Obj>(0)
+                if (range is ObjRange) {
+                    val index = range
+                    when {
+                        index.start is ObjInt && index.end is ObjInt -> {
+                            if (index.isEndInclusive)
+                                list.subList(index.start.toInt(), index.end.toInt() + 1)
+                            else
+                                list.subList(index.start.toInt(), index.end.toInt())
+                        }
+
+                        index.isOpenStart && !index.isOpenEnd -> {
+                            if (index.isEndInclusive)
+                                list.subList(0, index.end!!.toInt() + 1)
+                            else
+                                list.subList(0, index.end!!.toInt())
+                        }
+
+                        index.isOpenEnd && !index.isOpenStart -> {
+                            list.subList(index.start!!.toInt(), list.size)
+                        }
+
+                        index.isOpenStart && index.isOpenEnd -> {
+                            list
+                        }
+
+                        else -> {
+                            throw RuntimeException("Can't apply range for index: $index")
+                        }
+                    }.clear()
+                } else {
+                    val start = range.toInt()
+                    val end = requiredArg<ObjInt>(1).value.toInt() + 1
+                    self.list.subList(start, end).clear()
+                }
+                self
+            }
+        }
+    }
+}
+
+

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMap.kt

@@ -0,0 +1,173 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.Statement
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+
+class ObjMapEntry(val key: Obj, val value: Obj) : Obj() {
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is ObjMapEntry) return -1
+        val c = key.compareTo(scope, other.key)
+        if (c != 0) return c
+        return value.compareTo(scope, other.value)
+    }
+
+    override fun hashCode(): Int {
+        return key.hashCode() + value.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        return other is ObjMapEntry && key == other.key && value == other.value
+    }
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj = when (index.toInt()) {
+        0 -> key
+        1 -> value
+        else -> scope.raiseIndexOutOfBounds()
+    }
+
+    override fun toString(): String {
+        return "$key=>$value"
+    }
+
+    override val objClass = type
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeAny(scope,key)
+        encoder.encodeAny(scope,value)
+    }
+
+    companion object {
+        val type = object : ObjClass("MapEntry", ObjArray) {
+            override suspend fun callOn(scope: Scope): Obj {
+                return ObjMapEntry(scope.requiredArg<Obj>(0), scope.requiredArg<Obj>(1))
+            }
+
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj {
+                return ObjMapEntry(
+                    decoder.decodeAny(scope),
+                    decoder.decodeAny(scope)
+                )
+            }
+        }.apply {
+            addFn("key") { thisAs<ObjMapEntry>().key }
+            addFn("value") { thisAs<ObjMapEntry>().value }
+            addFn("size") { 2.toObj() }
+        }
+    }
+}
+
+class ObjMap(val map: MutableMap<Obj, Obj> = mutableMapOf()) : Obj() {
+
+    override val objClass = type
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj =
+        map.get(index) ?: ObjNull
+
+    override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
+        map[index] = newValue
+    }
+
+    override suspend fun contains(scope: Scope, other: Obj): Boolean {
+        return other in map
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if( other is ObjMap && other.map == map) return 0
+        return -1
+    }
+    override fun toString(): String = map.toString()
+
+    override fun hashCode(): Int {
+        return map.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjMap
+
+        return map == other.map
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.Map
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        val keys = map.keys.map { it.toObj() }
+        val values = map.values.map { it.toObj() }
+        encoder.encodeAnyList(scope, keys)
+        encoder.encodeAnyList(scope, values, fixedSize = true)
+    }
+
+    companion object {
+
+        suspend fun listToMap(scope: Scope, list: List<Obj>): MutableMap<Obj, Obj> {
+            val map = mutableMapOf<Obj, Obj>()
+            if (list.isEmpty()) return map
+
+            val first = list.first()
+            if (first.isInstanceOf(ObjArray)) {
+                if (first.invokeInstanceMethod(scope, "size").toInt() != 2)
+                    scope.raiseIllegalArgument(
+                        "list to construct map entry should exactly be 2 element Array like [key,value], got $list"
+                    )
+            } else scope.raiseIllegalArgument("first element of map list be a Collection of 2 elements; got $first")
+
+
+
+            list.forEach {
+                map[it.getAt(scope, ObjInt.Zero)] = it.getAt(scope, ObjInt.One)
+            }
+            return map
+        }
+
+
+        val type = object : ObjClass("Map", ObjCollection) {
+            override suspend fun callOn(scope: Scope): Obj {
+                return ObjMap(listToMap(scope, scope.args.list))
+            }
+
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj {
+                val keys = decoder.decodeAnyList(scope)
+                val values = decoder.decodeAnyList(scope,fixedSize = keys.size)
+                if( keys.size != values.size) scope.raiseIllegalArgument("map keys and values should be same size")
+                return ObjMap(keys.zip(values).toMap().toMutableMap())
+            }
+        }.apply {
+            addFn("getOrNull") {
+                val key = args.firstAndOnly(pos)
+                thisAs<ObjMap>().map.getOrElse(key) { ObjNull }
+            }
+            addFn("getOrPut") {
+                val key = requiredArg<Obj>(0)
+                thisAs<ObjMap>().map.getOrPut(key) {
+                    val lambda = requiredArg<Statement>(1)
+                    lambda.execute(this)
+                }
+            }
+            addFn("size") {
+                thisAs<ObjMap>().map.size.toObj()
+            }
+            addFn("remove") {
+                thisAs<ObjMap>().map.remove(requiredArg<Obj>(0))?.toObj() ?: ObjNull
+            }
+            addFn("clear") {
+                thisAs<ObjMap>().map.clear()
+                thisObj
+            }
+            addFn("keys") {
+                thisAs<ObjMap>().map.keys.toObj()
+            }
+            addFn("values") {
+                ObjList(thisAs<ObjMap>().map.values.toMutableList())
+            }
+            addFn("iterator") {
+                ObjKotlinIterator(thisAs<ObjMap>().map.entries.iterator())
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjMutableBuffer.kt

@@ -0,0 +1,71 @@
+package net.sergeych.lyng.obj
+
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.toList
+import net.sergeych.lyng.Scope
+
+class ObjMutableBuffer(byteArray: UByteArray) : ObjBuffer(byteArray) {
+
+    override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
+        byteArray[checkIndex(scope, index.toObj())] = when (newValue) {
+            is ObjInt -> newValue.value.toUByte()
+            is ObjChar -> newValue.value.code.toUByte()
+            else -> scope.raiseIllegalArgument(
+                "invalid byte value for buffer at index ${index.inspect()}: ${newValue.inspect()}"
+            )
+        }
+    }
+
+    companion object {
+
+        private suspend fun createBufferFrom(scope: Scope, obj: Obj): ObjBuffer =
+            when (obj) {
+                is ObjBuffer -> ObjMutableBuffer(obj.byteArray.copyOf())
+                is ObjInt -> {
+                    if (obj.value < 0)
+                        scope.raiseIllegalArgument("buffer size must be positive")
+                    val data = UByteArray(obj.value.toInt())
+                    ObjMutableBuffer(data)
+                }
+
+                is ObjString -> ObjMutableBuffer(obj.value.encodeToByteArray().asUByteArray())
+                else -> {
+                    if (obj.isInstanceOf(ObjIterable)) {
+                        ObjMutableBuffer(
+                            obj.toFlow(scope).map { it.toLong().toUByte() }.toList().toTypedArray()
+                                .toUByteArray()
+                        )
+                    } else
+                        scope.raiseIllegalArgument(
+                            "can't construct buffer from ${obj.inspect()}"
+                        )
+                }
+            }
+
+        val type = object : ObjClass("MutableBuffer", ObjBuffer.type) {
+            override suspend fun callOn(scope: Scope): Obj {
+                val args = scope.args.list
+                return when (args.size) {
+                    // empty buffer
+                    0 -> ObjMutableBuffer(ubyteArrayOf())
+                    1 -> createBufferFrom(scope, args[0])
+                    else -> {
+                        // create buffer from array, each argument should be a byte then:
+                        val data = UByteArray(args.size)
+                        for ((i, b) in args.withIndex()) {
+                            val code = when (b) {
+                                is ObjChar -> b.value.code.toUByte()
+                                is ObjInt -> b.value.toUByte()
+                                else -> scope.raiseIllegalArgument(
+                                    "invalid byte value for buffer constructor at index $i: ${b.inspect()}"
+                                )
+                            }
+                            data[i] = code
+                        }
+                        ObjMutableBuffer(data)
+                    }
+                }
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRange.kt

@@ -1,7 +1,12 @@
-package net.sergeych.lyng
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
 
 class ObjRange(val start: Obj?, val end: Obj?, val isEndInclusive: Boolean) : Obj() {
 
+    val isOpenStart by lazy { start == null || start.isNull }
+    val isOpenEnd by lazy { end == null || end.isNull }
+
     override val objClass: ObjClass = type
 
     override fun toString(): String {
@@ -12,10 +17,35 @@ class ObjRange(val start: Obj?, val end: Obj?, val isEndInclusive: Boolean) : Ob
         return result.toString()
     }
 
-    suspend fun containsRange(context: Context, other: ObjRange): Boolean {
+    /**
+     * IF end is open (null/ObjNull), returns null
+     * Otherwise, return correct value for the exclusive end
+     * raises [ObjIllegalArgumentException] if end is not ObjInt
+     */
+    fun exclusiveIntEnd(scope: Scope): Int? =
+        if (end == null || end is ObjNull) null
+        else {
+            if (end !is ObjInt) scope.raiseIllegalArgument("end is not int")
+            if (isEndInclusive) end.value.toInt() + 1 else end.value.toInt()
+        }
+
+
+    /**
+     * If start is null/ObjNull, returns 0
+     * if start is not ObjInt, raises [ObjIllegalArgumentException]
+     * otherwise returns start.value.toInt()
+     */
+    fun startInt(scope: Scope): Int =
+        if( start == null || start is ObjNull) 0
+        else {
+            if( start is ObjInt) start.value.toInt()
+            else scope.raiseIllegalArgument("start is not Int: ${start.inspect()}")
+        }
+
+    suspend fun containsRange(scope: Scope, other: ObjRange): Boolean {
         if (start != null) {
             // our start is not -∞ so other start should be GTE or is not contained:
-            if (other.start != null && start.compareTo(context, other.start) > 0) return false
+            if (other.start != null && start.compareTo(scope, other.start) > 0) return false
         }
         if (end != null) {
             // same with the end: if it is open, it can't be contained in ours:
@@ -23,16 +53,16 @@ class ObjRange(val start: Obj?, val end: Obj?, val isEndInclusive: Boolean) : Ob
             // both exists, now there could be 4 cases:
             return when {
                 other.isEndInclusive && isEndInclusive ->
-                    end.compareTo(context, other.end) >= 0
+                    end.compareTo(scope, other.end) >= 0
 
                 !other.isEndInclusive && !isEndInclusive ->
-                    end.compareTo(context, other.end) >= 0
+                    end.compareTo(scope, other.end) >= 0
 
                 other.isEndInclusive && !isEndInclusive ->
-                    end.compareTo(context, other.end) > 0
+                    end.compareTo(scope, other.end) > 0
 
                 !other.isEndInclusive && isEndInclusive ->
-                    end.compareTo(context, other.end) >= 0
+                    end.compareTo(scope, other.end) >= 0
 
                 else -> throw IllegalStateException("unknown comparison")
             }
@@ -40,17 +70,17 @@ class ObjRange(val start: Obj?, val end: Obj?, val isEndInclusive: Boolean) : Ob
         return true
     }
 
-    override suspend fun contains(context: Context, other: Obj): Boolean {
+    override suspend fun contains(scope: Scope, other: Obj): Boolean {
 
         if (other is ObjRange)
-            return containsRange(context, other)
+            return containsRange(scope, other)
 
         if (start == null && end == null) return true
         if (start != null) {
-            if (start.compareTo(context, other) > 0) return false
+            if (start.compareTo(scope, other) > 0) return false
         }
         if (end != null) {
-            val cmp = end.compareTo(context, other)
+            val cmp = end.compareTo(scope, other)
             if (isEndInclusive && cmp < 0 || !isEndInclusive && cmp <= 0) return false
         }
         return true
@@ -64,13 +94,34 @@ class ObjRange(val start: Obj?, val end: Obj?, val isEndInclusive: Boolean) : Ob
         start is ObjChar && end is ObjChar
     }
 
-    override suspend fun compareTo(context: Context, other: Obj): Int {
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
         return (other as? ObjRange)?.let {
             if( start == other.start && end == other.end ) 0 else -1
         }
             ?: -1
     }
 
+    override fun hashCode(): Int {
+        var result = start?.hashCode() ?: 0
+        result = 31 * result + (end?.hashCode() ?: 0)
+        result = 31 * result + isEndInclusive.hashCode()
+        return result
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjRange
+
+        if (start != other.start) return false
+        if (end != other.end) return false
+        if (isEndInclusive != other.isEndInclusive) return false
+
+        return true
+    }
+
+
     companion object {
         val type = ObjClass("Range", ObjIterable).apply {
             addFn("start") {

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRangeIterator.kt

@@ -1,4 +1,6 @@
-package net.sergeych.lyng
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
 
 class ObjRangeIterator(val self: ObjRange) : Obj() {
 
@@ -8,7 +10,7 @@ class ObjRangeIterator(val self: ObjRange) : Obj() {
 
     override val objClass: ObjClass = type
 
-    fun Context.init() {
+    fun Scope.init() {
         if (self.start == null || self.end == null)
             raiseError("next is only available for finite ranges")
         isCharRange = self.isCharRange
@@ -24,7 +26,7 @@ class ObjRangeIterator(val self: ObjRange) : Obj() {
 
     fun hasNext(): Boolean = nextIndex < lastIndex
 
-    fun next(context: Context): Obj =
+    fun next(scope: Scope): Obj =
         if (nextIndex < lastIndex) {
             val x = if (self.isEndInclusive)
                 self.start!!.toLong() + nextIndex++
@@ -33,7 +35,7 @@ class ObjRangeIterator(val self: ObjRange) : Obj() {
             if( isCharRange ) ObjChar(x.toInt().toChar()) else ObjInt(x)
         }
         else {
-            context.raiseError(ObjIterationFinishedException(context))
+            scope.raiseError(ObjIterationFinishedException(scope))
         }
 
     companion object {

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjReal.kt

@@ -0,0 +1,91 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Pos
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.statement
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+import kotlin.math.floor
+import kotlin.math.roundToLong
+
+data class ObjReal(val value: Double) : Obj(), Numeric {
+    override val asStr by lazy { ObjString(value.toString()) }
+    override val longValue: Long by lazy { floor(value).toLong() }
+    override val doubleValue: Double by lazy { value }
+    override val toObjInt: ObjInt by lazy { ObjInt(longValue) }
+    override val toObjReal: ObjReal by lazy { ObjReal(value) }
+
+    override val objClass: ObjClass = type
+
+    override fun byValueCopy(): Obj = ObjReal(value)
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is Numeric) return -2
+        return value.compareTo(other.doubleValue)
+    }
+
+    override fun toString(): String = value.toString()
+
+    override fun hashCode(): Int {
+        return value.hashCode()
+    }
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj =
+        ObjReal(this.value + other.toDouble())
+
+    override suspend fun minus(scope: Scope, other: Obj): Obj =
+        ObjReal(this.value - other.toDouble())
+
+    override suspend fun mul(scope: Scope, other: Obj): Obj =
+        ObjReal(this.value * other.toDouble())
+
+    override suspend fun div(scope: Scope, other: Obj): Obj =
+        ObjReal(this.value / other.toDouble())
+
+    override suspend fun mod(scope: Scope, other: Obj): Obj =
+        ObjReal(this.value % other.toDouble())
+
+    /**
+     * Returns unboxed Double value
+     */
+    override suspend fun toKotlin(scope: Scope): Any {
+        return value
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjReal
+
+        return value == other.value
+    }
+
+    override suspend fun negate(scope: Scope): Obj {
+        return ObjReal(-value)
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.Real
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeReal(value)
+    }
+
+    companion object {
+        val type: ObjClass = object : ObjClass("Real") {
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj =
+                ObjReal(decoder.unpackDouble())
+        }.apply {
+            createField(
+                "roundToInt",
+                statement(Pos.builtIn) {
+                    (it.thisObj as ObjReal).value.roundToLong().toObj()
+                },
+            )
+            addFn("toInt") {
+                ObjInt(thisAs<ObjReal>().value.toLong())
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjRecord.kt

@@ -0,0 +1,27 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.Visibility
+
+/**
+ * Record to store object with access rules, e.g. [isMutable] and access level [visibility].
+ */
+data class ObjRecord(
+    var value: Obj,
+    val isMutable: Boolean,
+    val visibility: Visibility = Visibility.Public,
+    var importedFrom: Scope? = null,
+    val isTransient: Boolean = false,
+    val type: Type = Type.Other
+) {
+    enum class Type(val comparable: Boolean = false,val serializable: Boolean = false) {
+        Field(true, true),
+        @Suppress("unused")
+        Fun,
+        ConstructorField(true, true),
+        Other
+    }
+    @Suppress("unused")
+    fun qualifiedName(name: String): String =
+        "${importedFrom?.packageName ?: "anonymous"}.$name"
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjSet.kt

@@ -0,0 +1,126 @@
+package net.sergeych.lyng.obj
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+
+class ObjSet(val set: MutableSet<Obj> = mutableSetOf()) : Obj() {
+
+    override val objClass = type
+
+    override suspend fun contains(scope: Scope, other: Obj): Boolean {
+        return set.contains(other)
+    }
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj {
+        return ObjSet(
+            if (other is ObjSet)
+                (set + other.set).toMutableSet()
+            else
+                (set + other).toMutableSet()
+        )
+    }
+
+    override suspend fun plusAssign(scope: Scope, other: Obj): Obj {
+        when (other) {
+            is ObjSet -> {
+                set += other.set
+            }
+
+            is ObjList -> {
+                set += other.list
+            }
+
+            else -> {
+                if (other.isInstanceOf(ObjIterable)) {
+                    val i = other.invokeInstanceMethod(scope, "iterable")
+                    while (i.invokeInstanceMethod(scope, "hasNext").toBool()) {
+                        set += i.invokeInstanceMethod(scope, "next")
+                    }
+                }
+                set += other
+            }
+        }
+        return this
+    }
+
+    override suspend fun mul(scope: Scope, other: Obj): Obj {
+        return if (other is ObjSet) {
+            ObjSet(set.intersect(other.set).toMutableSet())
+        } else
+            scope.raiseIllegalArgument("set operator * requires another set")
+    }
+
+    override suspend fun minus(scope: Scope, other: Obj): Obj {
+        if (other !is ObjSet)
+            scope.raiseIllegalArgument("set operator - requires another set")
+        return ObjSet(set.minus(other.set).toMutableSet())
+    }
+
+    override fun toString(): String {
+        return "Set(${set.joinToString(", ")})"
+    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        return if (other !is ObjSet) -1
+        else {
+            if (set == other.set) 0
+            else -1
+        }
+    }
+
+    override fun hashCode(): Int {
+        return set.hashCode()
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjSet
+
+        return set == other.set
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.Set
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeAnyList(scope, set.toList())
+    }
+
+    companion object {
+
+
+        val type = object : ObjClass("Set", ObjCollection) {
+            override suspend fun callOn(scope: Scope): Obj {
+                return ObjSet(scope.args.list.toMutableSet())
+            }
+
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj =
+                ObjSet(decoder.decodeAnyList(scope).toMutableSet())
+        }.apply {
+            addFn("size") {
+                thisAs<ObjSet>().set.size.toObj()
+            }
+            addFn("intersect") {
+                thisAs<ObjSet>().mul(this, args.firstAndOnly())
+            }
+            addFn("iterator") {
+                thisAs<ObjSet>().set.iterator().toObj()
+            }
+            addFn("union") {
+                thisAs<ObjSet>().plus(this, args.firstAndOnly())
+            }
+            addFn("subtract") {
+                thisAs<ObjSet>().minus(this, args.firstAndOnly())
+            }
+            addFn("remove") {
+                val set = thisAs<ObjSet>().set
+                val n = set.size
+                for( x in args.list ) set -= x
+                if( n == set.size ) ObjFalse else ObjTrue
+            }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/obj/ObjString.kt

@@ -0,0 +1,143 @@
+package net.sergeych.lyng.obj
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.statement
+import net.sergeych.lynon.LynonDecoder
+import net.sergeych.lynon.LynonEncoder
+import net.sergeych.lynon.LynonType
+import net.sergeych.sprintf.sprintf
+
+@Serializable
+@SerialName("string")
+data class ObjString(val value: String) : Obj() {
+
+//    fun normalize(context: Context, index: Int, allowsEndInclusive: Boolean = false): Int {
+//        val i = if (index < 0) value.length + index else index
+//        if (allowsEndInclusive && i == value.length) return i
+//        if (i !in value.indices) context.raiseError("index $index out of bounds for length ${value.length} of \"$value\"")
+//        return i
+//    }
+
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
+        if (other !is ObjString) return -2
+        return this.value.compareTo(other.value)
+    }
+
+    override fun toString(): String = value
+
+    override val asStr: ObjString by lazy { this }
+
+    override fun inspect(): String {
+        return "\"$value\""
+    }
+
+    override val objClass: ObjClass
+        get() = type
+
+    override suspend fun plus(scope: Scope, other: Obj): Obj {
+        return ObjString(value + other.asStr.value)
+    }
+
+    override suspend fun getAt(scope: Scope, index: Obj): Obj {
+        if (index is ObjInt) return ObjChar(value[index.toInt()])
+        if (index is ObjRange) {
+            val start = if (index.start == null || index.start.isNull) 0 else index.start.toInt()
+            val end = if (index.end == null || index.end.isNull) value.length else {
+                val e = index.end.toInt()
+                if (index.isEndInclusive) e + 1 else e
+            }
+            return ObjString(value.substring(start, end))
+        }
+        scope.raiseIllegalArgument("String index must be Int or Range")
+    }
+
+    override fun hashCode(): Int {
+        return value.hashCode()
+    }
+
+    override suspend fun callOn(scope: Scope): Obj {
+        return ObjString(this.value.sprintf(*scope.args
+            .toKotlinList(scope)
+            .map { if (it == null) "null" else it }
+            .toTypedArray()))
+    }
+
+    override suspend fun contains(scope: Scope, other: Obj): Boolean {
+        return if (other is ObjString)
+            value.contains(other.value)
+        else if (other is ObjChar)
+            value.contains(other.value)
+        else scope.raiseIllegalArgument("String.contains can't take $other")
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as ObjString
+
+        return value == other.value
+    }
+
+    override suspend fun lynonType(): LynonType = LynonType.String
+
+    override suspend fun serialize(scope: Scope, encoder: LynonEncoder, lynonType: LynonType?) {
+        encoder.encodeBinaryData(value.encodeToByteArray())
+    }
+
+    companion object {
+        val type = object : ObjClass("String") {
+            override suspend fun deserialize(scope: Scope, decoder: LynonDecoder, lynonType: LynonType?): Obj =
+                ObjString(decoder.unpackBinaryData().decodeToString())
+        }.apply {
+            addFn("toInt") {
+                ObjInt(thisAs<ObjString>().value.toLong())
+            }
+            addFn("startsWith") {
+                ObjBool(thisAs<ObjString>().value.startsWith(requiredArg<ObjString>(0).value))
+            }
+            addFn("endsWith") {
+                ObjBool(thisAs<ObjString>().value.endsWith(requiredArg<ObjString>(0).value))
+            }
+            addConst("length",
+                statement { ObjInt(thisAs<ObjString>().value.length.toLong()) }
+            )
+            addFn("takeLast") {
+                thisAs<ObjString>().value.takeLast(
+                    requiredArg<ObjInt>(0).toInt()
+                ).let(::ObjString)
+            }
+            addFn("take") {
+                thisAs<ObjString>().value.take(
+                    requiredArg<ObjInt>(0).toInt()
+                ).let(::ObjString)
+            }
+            addFn("drop") {
+                thisAs<ObjString>().value.drop(
+                    requiredArg<ObjInt>(0).toInt()
+                ).let(::ObjString)
+            }
+            addFn("dropLast") {
+                thisAs<ObjString>().value.dropLast(
+                    requiredArg<ObjInt>(0).toInt()
+                ).let(::ObjString)
+            }
+            addFn("lower") {
+                thisAs<ObjString>().value.lowercase().let(::ObjString)
+            }
+            addFn("upper") {
+                thisAs<ObjString>().value.uppercase().let(::ObjString)
+            }
+            addFn("characters") {
+                ObjList(
+                    thisAs<ObjString>().value.map { ObjChar(it) }.toMutableList()
+                )
+            }
+            addFn("encodeUtf8") { ObjBuffer(thisAs<ObjString>().value.encodeToByteArray().asUByteArray()) }
+            addFn("size") { ObjInt(thisAs<ObjString>().value.length.toLong()) }
+            addFn("toReal") { ObjReal(thisAs<ObjString>().value.toDouble()) }
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/pacman/ImportManager.kt

@@ -0,0 +1,141 @@
+package net.sergeych.lyng.pacman
+
+import net.sergeych.lyng.*
+import net.sergeych.synctools.ProtectedOp
+import net.sergeych.synctools.withLock
+
+/**
+ * Import manager allow to register packages with builder lambdas and act as an
+ * [ImportProvider]. Note that packages _must be registered_ first with [addPackage],
+ * [addSourcePackages] or [addTextPackages]. Registration is cheap, actual package
+ * building is lazily performed on [createModuleScope], when the package will
+ * be first imported.
+ *
+ * It is possible to register new packages at any time, but it is not allowed to override
+ * packages already registered.
+ */
+class ImportManager(
+    rootScope: Scope = Script.defaultImportManager.newModule(),
+    securityManager: SecurityManager = SecurityManager.allowAll
+) : ImportProvider(rootScope, securityManager) {
+
+    val packageNames: List<String> get() = imports.keys.toList()
+
+    private inner class Entry(
+        val packageName: String,
+        val builder: suspend (ModuleScope) -> Unit,
+        var cachedScope: ModuleScope? = null
+    ) {
+
+        suspend fun getScope(pos: Pos): ModuleScope {
+            cachedScope?.let { return it }
+            return ModuleScope(inner, pos, packageName).apply {
+                cachedScope = this
+                builder(this)
+            }
+        }
+    }
+
+
+    /**
+     * Inner provider does not lock [op], the only difference; it is meant to be used
+     * exclusively by the coroutine that starts actual import chain
+     */
+    private inner class InternalProvider : ImportProvider(rootScope) {
+        override suspend fun createModuleScope(pos: Pos, packageName: String): ModuleScope {
+            return doImport(packageName, pos)
+        }
+
+        override fun getActualProvider(): ImportProvider {
+            return this@ImportManager
+        }
+    }
+
+    /**
+     * Inner module import provider used to prepare lazily prepared modules
+     */
+    private val inner = InternalProvider()
+
+
+    private val imports = mutableMapOf<String, Entry>()
+
+    val op = ProtectedOp()
+
+
+    /**
+     * Register new package that can be imported. It is not possible to unregister or
+     * update package already registered.
+     *
+     * Packages are lazily created when first imported somewhere, so the registration is
+     * cheap; the recommended procedure is to register all available packages prior to
+     * compile with this.
+     *
+     * @param name package name
+     * @param builder lambda to create actual package using the given [ModuleScope]
+     */
+    fun addPackage(name: String, builder: suspend (ModuleScope) -> Unit) {
+        op.withLock {
+            if (name in imports)
+                throw IllegalArgumentException("Package $name already exists")
+            imports[name] = Entry(name, builder)
+        }
+    }
+
+    /**
+     * Bulk [addPackage] with slightly better performance
+     */
+    @Suppress("unused")
+    fun addPackages(registrationData: List<Pair<String, suspend (ModuleScope) -> Unit>>) {
+        op.withLock {
+            for (pp in registrationData) {
+                if (pp.first in imports)
+                    throw IllegalArgumentException("Package ${pp.first} already exists")
+                imports[pp.first] = Entry(pp.first, pp.second)
+            }
+        }
+    }
+
+    /**
+     * Perform actual import or return ready scope. __It must only be called when
+     * [op] is locked__, e.g. only internally
+     */
+    private suspend fun doImport(packageName: String, pos: Pos): ModuleScope {
+        val entry = imports[packageName] ?: throw ImportException(pos, "package not found: $packageName")
+        return entry.getScope(pos)
+    }
+
+    override suspend fun createModuleScope(pos: Pos, packageName: String): ModuleScope =
+        doImport(packageName, pos)
+
+    /**
+     * Add packages that only need to compile [Source].
+     */
+    fun addSourcePackages(vararg sources: Source) {
+        for (s in sources) {
+            addPackage(s.extractPackageName()) {
+                it.eval(s)
+            }
+
+        }
+    }
+
+    /**
+     * Add source packages using package name as [Source.fileName], for simplicity
+     */
+    fun addTextPackages(vararg sourceTexts: String) {
+        for (s in sourceTexts) {
+            var source = Source("tmp", s)
+            val packageName = source.extractPackageName()
+            source = Source(packageName, s)
+            addPackage(packageName) { it.eval(source) }
+        }
+    }
+
+    fun copy(): ImportManager =
+        op.withLock {
+            ImportManager(rootScope, securityManager).apply {
+                imports.putAll(this@ImportManager.imports)
+            }
+        }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/pacman/ImportProvider.kt

@@ -0,0 +1,51 @@
+package net.sergeych.lyng.pacman
+
+import net.sergeych.lyng.*
+
+/**
+ * Package manager INTERFACE (abstract class). Performs import routines
+ * using abstract [createModuleScope] method ot be implemented by heirs.
+ *
+ * Notice that [createModuleScope] is responsible for caching the modules;
+ * base class relies on caching. This is not implemented here as the correct
+ * caching strategy depends on the import provider
+ */
+abstract class ImportProvider(
+    val rootScope: Scope,
+    val securityManager: SecurityManager = SecurityManager.allowAll
+) {
+
+    open fun getActualProvider() = this
+
+    /**
+     * Find an import and create a scope for it. This method must implement caching so repeated
+     * imports are not repeatedly loaded and parsed and should be cheap.
+     *
+     * @throws ImportException if the module is not found
+     */
+    abstract suspend fun createModuleScope(pos: Pos,packageName: String): ModuleScope
+
+    /**
+     * Check that the import is possible and allowed. This method is called on compile time by [Compiler];
+     * actual module loading is performed by [ModuleScope.importInto]
+     */
+    suspend fun prepareImport(pos: Pos, name: String, symbols: Map<String, String>?): ModuleScope {
+        if (!securityManager.canImportModule(name))
+            throw ImportException(pos, "Module $name is not allowed")
+        symbols?.keys?.forEach {
+            if (!securityManager.canImportSymbol(name, it)) throw ImportException(
+                pos,
+                "Symbol $name.$it is not allowed"
+            )
+        }
+        return createModuleScope(pos, name)
+    }
+
+    fun newModule() = newModuleAt(Pos.builtIn)
+
+    fun newModuleAt(pos: Pos): ModuleScope =
+        ModuleScope(this, pos, "unknown")
+}
+
+
+

lynglib/src/commonMain/kotlin/net/sergeych/lyng/pacman/InlineSourcesImportProvider.kt

@@ -0,0 +1,35 @@
+package net.sergeych.lyng.pacman
+
+import kotlinx.coroutines.CompletableDeferred
+import net.sergeych.lyng.*
+import net.sergeych.mp_tools.globalLaunch
+
+/**
+ * The sample import provider that imports sources available in memory.
+ * on construction time.
+ *
+ * Actually it is left here only as a demo.
+ */
+class InlineSourcesImportProvider(sources: List<Source>,
+                                  rootScope: ModuleScope = Script.defaultImportManager.newModule(),
+                                  securityManager: SecurityManager = SecurityManager.allowAll
+) : ImportProvider(rootScope) {
+
+    private val manager = ImportManager(rootScope, securityManager)
+
+    private val readyManager = CompletableDeferred<ImportManager>()
+
+    /**
+     * This implementation only
+     */
+    override suspend fun createModuleScope(pos: Pos, packageName: String): ModuleScope {
+        return readyManager.await().createModuleScope(pos, packageName)
+    }
+
+    init {
+        globalLaunch {
+            manager.addSourcePackages(*sources.toTypedArray())
+            readyManager.complete(manager)
+        }
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/statements.kt

@@ -1,31 +1,38 @@
 package net.sergeych.lyng
 
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjClass
+import net.sergeych.lyng.obj.ObjVoid
+
 fun String.toSource(name: String = "eval"): Source = Source(name, this)
 
 sealed class ObjType {
     object Any : ObjType()
-    object Int : ObjType()
+    object Void: ObjType()
+
+    companion object {
+    }
 }
 
 
 @Suppress("unused")
 abstract class Statement(
     val isStaticConst: Boolean = false,
-    val isConst: Boolean = false,
+    override val isConst: Boolean = false,
     val returnType: ObjType = ObjType.Any
 ) : Obj() {
 
     override val objClass: ObjClass = type
 
     abstract val pos: Pos
-    abstract suspend fun execute(context: Context): Obj
+    abstract suspend fun execute(scope: Scope): Obj
 
-    override suspend fun compareTo(context: Context,other: Obj): Int {
+    override suspend fun compareTo(scope: Scope, other: Obj): Int {
         throw UnsupportedOperationException("not comparable")
     }
 
-    override suspend fun callOn(context: Context): Obj {
-        return execute(context)
+    override suspend fun callOn(scope: Scope): Obj {
+        return execute(scope)
     }
 
     override fun toString(): String = "Callable@${this.hashCode()}"
@@ -34,6 +41,8 @@ abstract class Statement(
         val type = ObjClass("Callable")
     }
 
+    suspend fun call(scope: Scope, vararg args: Obj) = execute(scope.copy(args =  Arguments(*args)))
+
 }
 
 fun Statement.raise(text: String): Nothing {
@@ -45,16 +54,20 @@ fun Statement.require(cond: Boolean, message: () -> String) {
     if (!cond) raise(message())
 }
 
-fun statement(pos: Pos, isStaticConst: Boolean = false, isConst: Boolean = false, f: suspend (Context) -> Obj): Statement =
+fun statement(pos: Pos, isStaticConst: Boolean = false, isConst: Boolean = false, f: suspend (Scope) -> Obj): Statement =
     object : Statement(isStaticConst, isConst) {
         override val pos: Pos = pos
-        override suspend fun execute(context: Context): Obj = f(context)
+        override suspend fun execute(scope: Scope): Obj = f(scope)
     }
 
-fun statement(isStaticConst: Boolean = false, isConst: Boolean = false, f: suspend Context.() -> Obj): Statement =
+fun statement(isStaticConst: Boolean = false, isConst: Boolean = false, f: suspend Scope.() -> Obj): Statement =
     object : Statement(isStaticConst, isConst) {
         override val pos: Pos = Pos.builtIn
-        override suspend fun execute(context: Context): Obj = f(context)
+        override suspend fun execute(scope: Scope): Obj = f(scope)
     }
 
+object NopStatement: Statement(true, true, ObjType.Void) {
+    override val pos: Pos = Pos.builtIn
 
+    override suspend fun execute(scope: Scope): Obj = ObjVoid
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitInput.kt

@@ -0,0 +1,90 @@
+package net.sergeych.lynon
+
+interface BitInput {
+
+
+    fun getBitOrNull(): Int?
+
+    fun getBitsOrNull(count: Int): ULong? {
+        var result = 0UL
+        var resultMask = 1UL
+        for( i in 0 ..< count) {
+            when(getBitOrNull()) {
+                null -> return null
+                1 -> result = result or resultMask
+                0 -> {}
+            }
+            resultMask = resultMask shl 1
+        }
+        return result
+    }
+
+    fun getBits(count: Int): ULong {
+        return getBitsOrNull(count) ?: throw IllegalStateException("Unexpected end of stream")
+    }
+
+    fun getBit(): Int {
+        return getBitOrNull() ?: throw IllegalStateException("Unexpected end of stream")
+    }
+
+    fun unpackUnsigned(): ULong =
+        unpackUnsignedOrNull() ?: throw IllegalStateException("Unexpected end of stream")
+
+    fun unpackUnsignedOrNull(): ULong? {
+        val tetrades = getBitsOrNull(4)?.toInt() ?: return null
+        var result = 0UL
+        var shift = 0
+        for (i in 0.. tetrades) {
+            result = result or (getBits(4) shl shift)
+            shift += 4
+        }
+        return result
+    }
+
+    fun unpackSigned(): Long {
+        val isNegative = getBit()
+        val value = unpackUnsigned().toLong()
+        return if( isNegative == 1) -value else value
+    }
+
+    @Suppress("unused")
+    fun getBool(): Boolean {
+        return getBit() == 1
+    }
+
+    fun getBytes(count: Int): ByteArray? {
+        val result = ByteArray(count)
+        for (i in 0..<count) {
+            val b = getBitsOrNull(8) ?: return null
+            result[i] = b.toByte()
+        }
+        return result
+    }
+
+
+    fun decompress(): ByteArray = decompressOrNull() ?: throw DecompressionException("Unexpected end of stream")
+
+    fun decompressOrNull(): ByteArray? {
+        val originalSize = unpackUnsignedOrNull()?.toInt() ?: return null
+        return if( getBit() == 1) {
+            // data is compressed
+//            val expectedCRC = getBits(32).toUInt()
+            val method = getBits(2).toInt()
+            if( method != 0) throw DecompressionException("Unknown compression method")
+            LZW.decompress(this, originalSize).asByteArray()
+        }
+        else {
+            getBytes(originalSize) ?: throw DecompressionException("Unexpected end of stream in uncompressed data")
+        }
+    }
+
+    @Suppress("unused")
+    fun decompressStringOrNull(): String? = decompressOrNull()?.decodeToString()
+
+    fun decompressString(): String = decompress().decodeToString()
+    fun unpackDouble(): Double {
+        val bits = getBits(64)
+        return Double.fromBits(bits.toLong())
+    }
+}
+

lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitList.kt

@@ -0,0 +1,34 @@
+package net.sergeych.lynon
+
+@Suppress("unused")
+interface BitList {
+    operator fun get(bitIndex: Long): Int
+    operator fun set(bitIndex: Long,value: Int)
+    val size: Long
+    val indices: LongRange
+
+    fun toInput(): BitInput = object : BitInput {
+        private var index = 0L
+
+        override fun getBitOrNull(): Int? =
+            if( index < size) this@BitList[index++]
+            else null
+    }
+}
+
+fun bitListOf(vararg bits: Int): BitList {
+    return if( bits.size > 64) {
+        BitArray.ofBits(*bits)
+    }
+    else
+        TinyBits.of(*bits)
+}
+
+@Suppress("unused")
+fun bitListOfSize(sizeInBits: Long): BitList {
+    return if( sizeInBits > 64) {
+        BitArray.withBitSize(sizeInBits)
+    }
+    else
+        TinyBits()
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/BitOutput.kt

@@ -0,0 +1,104 @@
+package net.sergeych.lynon
+
+interface BitOutput {
+
+    fun putBits(bits: ULong, count: Int) {
+        require(count <= 64)
+        var x = bits
+        for (i in 0..<count) {
+            putBit((x and 1u).toInt())
+            x = x shr 1
+        }
+    }
+
+    fun putBits(bits: Int, count: Int) {
+        require(count <= 32)
+        var x = bits
+        for (i in 0..<count) {
+            putBit((x and 1))
+            x = x shr 1
+        }
+    }
+
+    fun putBit(bit: Int)
+
+    fun putBits(bitList: BitList) {
+        for (i in bitList.indices)
+            putBit(bitList[i])
+    }
+
+    fun packUnsigned(value: ULong) {
+        val tetrades = sizeInTetrades(value)
+        putBits(tetrades - 1, 4)
+        var rest = value
+        for (i in 0..<tetrades) {
+            putBits(rest and 0xFu, 4)
+            rest = rest shr 4
+        }
+    }
+
+    @Suppress("unused")
+    fun packSigned(value: Long) {
+        if (value < 0) {
+            putBit(1)
+            packUnsigned((-value).toULong())
+        } else {
+            putBit(0)
+            packUnsigned(value.toULong())
+        }
+    }
+
+    fun putBytes(data: ByteArray) {
+        for (b in data) {
+            putBits(b.toULong(), 8)
+        }
+    }
+
+
+    /**
+     * Create compressed record with content and size check. Compression works with _bytes_.
+     *
+     * Structure:
+     *
+     * | size | meaning                                          |
+     * |------|--------------------------------------------------|
+     * | packed unsigned | size of uncompressed content in bytes |
+     * | 1               | 0 - not compressed, 1 - compressed |
+     *
+     * __If compressed__, then:
+     *
+     * | size | meaning                              |
+     * |------|--------------------------------------|
+     * |  2   | 00 - LZW, other combinations reserved|
+     *
+     * After this header compressed bits follow.
+     *
+     * __If not compressed,__ then source data follows as bit stream.
+     *
+     * Compressed block overhead is 3 bits, uncompressed 1.
+     */
+    fun compress(source: ByteArray) {
+        // size
+        packUnsigned(source.size.toULong())
+        // check compression is effective?
+        val compressed = LZW.compress(source.asUByteArray())
+        // check that compression is effective including header bits size:
+        if( compressed.size + 2 < source.size * 8L) {
+            println("write compressed")
+            putBit(1)
+            // LZW algorithm
+            putBits(0, 2)
+            // compressed data
+            putBits(compressed)
+        }
+        else {
+            putBit(0)
+            putBytes(source)
+        }
+    }
+
+    fun compress(source: String) {
+        compress(source.encodeToByteArray())
+    }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/DecompressionException.kt

@@ -0,0 +1,3 @@
+package net.sergeych.lynon
+
+class DecompressionException(message: String) : IllegalArgumentException(message) {}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/LynonDecoder.kt

@@ -0,0 +1,106 @@
+package net.sergeych.lynon
+
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.obj.Obj
+import net.sergeych.lyng.obj.ObjClass
+import net.sergeych.lyng.obj.ObjString
+
+open class LynonDecoder(val bin: BitInput, val settings: LynonSettings = LynonSettings.default) {
+
+    fun getBitsAsInt(bitsSize: Int): Int {
+        return bin.getBits(bitsSize).toInt()
+    }
+
+    fun unpackUnsignedInt(): Int = bin.unpackUnsigned().toInt()
+
+    fun decompress() = bin.decompress()
+
+    val cache = mutableListOf<Any>()
+
+
+    inline fun <reified T : Any> decodeCached(f: LynonDecoder.() -> T): T {
+        return if (bin.getBit() == 0) {
+            // unpack and cache
+            f().also {
+//                println("decode: cache miss: ${cache.size}: $it:${it::class.simpleName}")
+                if (settings.shouldCache(it)) cache.add(it)
+            }
+        } else {
+            // get cache reference
+            val size = sizeInBits(cache.size)
+            val id = bin.getBitsOrNull(size)?.toInt()
+                ?: throw RuntimeException("Invalid object id: unexpected end of stream")
+            if (id >= cache.size) throw RuntimeException("Invalid object id: $id should be in 0..<${cache.size}")
+//            println("decode: cache hit ${id}: ${cache[id]}:${cache[id]::class.simpleName}")
+//            @Suppress("UNCHECKED_CAST")
+            cache[id] as T
+        }
+    }
+
+    suspend fun decodeAny(scope: Scope): Obj = decodeCached {
+        val type = LynonType.entries[bin.getBits(4).toInt()]
+        if (type != LynonType.Other) {
+            type.objClass.deserialize(scope, this, type)
+        } else {
+            decodeClassObj(scope).deserialize(scope, this, null)
+        }
+    }
+
+    private suspend fun decodeClassObj(scope: Scope): ObjClass {
+        val className = decodeObject(scope, ObjString.type, null) as ObjString
+        println("expected class name $className")
+        return scope.get(className.value)?.value?.let {
+            if (it !is ObjClass)
+                scope.raiseClassCastError("Expected obj class but got ${it::class.simpleName}")
+            it
+        } ?: scope.raiseSymbolNotFound("can't deserialize: not found type $className")
+    }
+
+    suspend fun decodeAnyList(scope: Scope,fixedSize: Int?=null): MutableList<Obj> {
+        return if (bin.getBit() == 1) {
+            // homogenous
+            val type = LynonType.entries[getBitsAsInt(4)]
+            val list = mutableListOf<Obj>()
+            val objClass = if (type == LynonType.Other)
+                decodeClassObj(scope).also { println("detected class obj: $it") }
+            else type.objClass
+            val size = fixedSize ?: bin.unpackUnsigned().toInt()
+            println("detected homogenous list type $type, $size items")
+            for (i in 0..<size) {
+                list += decodeObject(scope, objClass, type).also {
+                    println("decoded: $it")
+                }
+            }
+            list
+        } else {
+            val size = fixedSize ?: unpackUnsigned().toInt()
+            (0..<size).map { decodeAny(scope) }.toMutableList()
+        }
+    }
+
+    suspend fun decodeObject(scope: Scope, type: ObjClass, overrideType: LynonType? = null): Obj {
+        return decodeCached { type.deserialize(scope, this, overrideType) }
+    }
+
+    fun unpackBinaryData(): ByteArray = bin.decompress()
+
+    @Suppress("unused")
+    fun unpackBinaryDataOrNull(): ByteArray? = bin.decompressOrNull()
+
+    fun unpackBoolean(): Boolean {
+        return bin.getBit() == 1
+    }
+
+    fun unpackDouble(): Double {
+        return Double.fromBits(bin.getBits(64).toLong())
+    }
+
+    fun unpackSigned(): Long {
+        return bin.unpackSigned()
+    }
+
+    fun unpackUnsigned(): ULong {
+        return bin.unpackUnsigned()
+    }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/LynonEncoder.kt

@@ -0,0 +1,194 @@
+package net.sergeych.lynon
+
+import net.sergeych.bintools.ByteChunk
+import net.sergeych.lyng.Scope
+import net.sergeych.lyng.obj.*
+
+enum class LynonType(val objClass: ObjClass, val defaultFrequency: Int = 1) {
+    Null(ObjNull.objClass, 80),
+    Int0(ObjInt.type, 70),
+    IntNegative(ObjInt.type, 50),
+    IntPositive(ObjInt.type, 100),
+    IntSigned(ObjInt.type, 30),
+    String(ObjString.type, 100),
+    Real(ObjReal.type),
+    Bool(ObjBool.type, 80),
+    List(ObjList.type, 70),
+    Map(ObjMap.type, 40),
+    Set(ObjSet.type),
+    Buffer(ObjBuffer.type, 50),
+    Instant(ObjInstant.type, 30),
+    Duration(ObjDuration.type),
+    Other(Obj.rootObjectType, 60);
+
+    fun generalizeTo(other: LynonType): LynonType? {
+        if (this == other) return this
+        return (if (this.isInt && other.isInt) {
+            when {
+                this == Int0 -> other // upgrade 0 to some other int
+                other == Int0 -> this // 0 is member of our class, ignore
+                // different signum propagate to signed
+                else -> IntSigned
+            }
+        } else
+        // impossible to generalize
+            null
+                ).also { println("Gen $this + $other -> $it") }
+    }
+
+    val isInt by lazy {
+        when (this) {
+            Int0, IntSigned, IntPositive, IntNegative -> true
+            else -> false
+        }
+    }
+
+}
+
+open class LynonEncoder(val bout: BitOutput, val settings: LynonSettings = LynonSettings.default) {
+
+    val cache = mutableMapOf<Any, Int>()
+
+    suspend fun encodeCached(item: Any, packer: suspend LynonEncoder.() -> Unit) {
+
+        suspend fun serializeAndCache(key: Any = item) {
+            cache[key]?.let { cacheId ->
+//                println("encode: Cache hit: ${cacheId}: $item: ${item::class.simpleName}")
+                val size = sizeInBits(cache.size)
+                bout.putBit(1)
+                bout.putBits(cacheId.toULong(), size)
+            } ?: run {
+                bout.putBit(0)
+                if (settings.shouldCache(item)) {
+//                    println("encode add cache: ${cache.size}: $item: ${item::class.simpleName}")
+                    packer()
+                    cache[key] = cache.size
+                } else {
+//                    println("encode but not cache $item")
+                    packer()
+                }
+            }
+        }
+
+        when (item) {
+            is ByteArray -> serializeAndCache(ByteChunk(item.asUByteArray()))
+            is UByteArray -> serializeAndCache(ByteChunk(item))
+            else -> serializeAndCache(item)
+        }
+    }
+
+    /**
+     * Encode any Lyng object [Obj], which can be serialized, using type record. This allow to
+     * encode any object with the overhead of type record.
+     *
+     * Caching is used automatically.
+     */
+    suspend fun encodeAny(scope: Scope, obj: Obj) {
+        encodeCached(obj) {
+            val type = putTypeRecord(scope, obj, obj.lynonType())
+            obj.serialize(scope, this, type)
+        }
+    }
+
+    private suspend fun putTypeRecord(scope: Scope, obj: Obj, type: LynonType): LynonType {
+        putType(type)
+        if( type == LynonType.Other) {
+            encodeObject(scope, obj.objClass.classNameObj)
+        }
+        return type
+    }
+
+    private fun putType(type: LynonType) {
+        bout.putBits(type.ordinal.toULong(), 4)
+    }
+
+    /**
+     * AnyList could be homogenous (first bit=1) and heterogeneous (first bit=0). Homogenous list
+     * has a single type record that precedes the list, heterogeneous hash typed record
+     * for each item.
+     *
+     */
+    suspend fun encodeAnyList(scope: Scope, list: List<Obj>,fixedSize: Boolean = false) {
+        if( list.isEmpty()) {
+            // any-typed, empty, save space
+            putBit(0)
+            encodeUnsigned(0u)
+        }
+        else {
+            val objClass = list[0].objClass
+            var type = list[0].lynonType()
+            var isHomogeneous = true
+            for (i in list.drop(1))
+                if (i.objClass != objClass) {
+                    isHomogeneous = false
+                    break
+                } else {
+                    // same class but type might need generalization
+                    type = type.generalizeTo(i.lynonType())
+                        ?: scope.raiseError("inner error: can't generalize lynon type $type to ${i.lynonType()}")
+                }
+            if (isHomogeneous) {
+                putBit(1)
+                putTypeRecord(scope, list[0], type)
+                if (!fixedSize)
+                    encodeUnsigned(list.size.toULong())
+                for (i in list) encodeObject(scope, i, type)
+            } else {
+                putBit(0)
+                if (!fixedSize)
+                    encodeUnsigned(list.size.toULong())
+                for (i in list) encodeAny(scope, i)
+            }
+        }
+    }
+
+    /**
+     * Write object _with no type record_: type is known
+     */
+    suspend fun encodeObject(scope: Scope, obj: Obj,overrideType: LynonType? = null) {
+        encodeCached(obj) {
+            obj.serialize(scope, this, overrideType)
+        }
+    }
+
+    suspend fun encodeCachedBytes(bytes: ByteArray) {
+        encodeCached(bytes) {
+            bout.compress(bytes)
+        }
+    }
+
+    fun encodeBinaryData(data: ByteArray) {
+        bout.compress(data)
+    }
+
+    fun encodeSigned(value: Long) {
+        bout.packSigned(value)
+    }
+
+    @Suppress("unused")
+    fun encodeUnsigned(value: ULong) {
+        bout.packUnsigned(value)
+    }
+
+    @Suppress("unused")
+    fun encodeBool(value: Boolean) {
+        bout.putBit(if (value) 1 else 0)
+    }
+
+    fun encodeReal(value: Double) {
+        bout.putBits(value.toRawBits().toULong(), 64)
+    }
+
+    fun encodeBoolean(value: Boolean) {
+        bout.putBit(if (value) 1 else 0)
+    }
+
+    fun putBits(value: Int, sizeInBits: Int) {
+        bout.putBits(value.toULong(), sizeInBits)
+    }
+
+    fun putBit(bit: Int) {
+        bout.putBit(bit)
+    }
+
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/LynonSettings.kt

@@ -0,0 +1,29 @@
+package net.sergeych.lynon
+
+import net.sergeych.lyng.obj.ObjBool
+import net.sergeych.lyng.obj.ObjChar
+import net.sergeych.lyng.obj.ObjInt
+import net.sergeych.lyng.obj.ObjNull
+import kotlin.math.absoluteValue
+
+open class LynonSettings {
+    enum class InstantTruncateMode {
+        Second,
+        Millisecond,
+        Microsecond
+    }
+
+    open fun shouldCache(obj: Any): Boolean = when (obj) {
+        is ObjChar -> false
+        is ObjInt -> obj.value.absoluteValue > 0x10000FF
+        is ObjBool -> false
+        is ObjNull -> false
+        is ByteArray -> obj.size > 2
+        is UByteArray -> obj.size > 2
+        else -> true
+    }
+
+    companion object {
+        val default = LynonSettings()
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lynon/MemoryBitInput.kt

@@ -0,0 +1,40 @@
+package net.sergeych.lynon
+
+
+class MemoryBitInput(val packedBits: UByteArray, val lastByteBits: Int) : BitInput {
+
+    constructor(ba: BitArray) : this(ba.bytes, ba.lastByteBits) {}
+    constructor(mba: MemoryBitOutput) : this(mba.toBitArray()) {}
+
+    private var index = 0
+
+    private var isEndOfStream: Boolean = packedBits.isEmpty() || (packedBits.size == 1 && lastByteBits == 0)
+        private set
+
+    /**
+     * Return next byte, int in 0..255 range, or -1 if end of stream reached
+     */
+    private var accumulator = if( isEndOfStream ) 0 else packedBits[0].toInt()
+
+    private var bitCounter = 0
+
+    override fun getBitOrNull(): Int? {
+        if (isEndOfStream) return null
+        val result = accumulator and 1
+        accumulator = accumulator shr 1
+        bitCounter++
+        // is end?
+        if( index == packedBits.lastIndex && bitCounter == lastByteBits ) {
+            isEndOfStream = true
+        }
+        else {
+            if( bitCounter == 8 ) {
+                bitCounter = 0
+                accumulator = packedBits[++index].toInt()
+            }
+        }
+        return result
+    }
+
+
+}