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@ -16,7 +16,8 @@ __Other documents to read__ maybe after this one:
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- [math in Lyng](math.md)
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- [parallelism] - multithreaded code, coroutines, etc.
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- Some class references: [List], [Set], [Map], [Real], [Range], [Iterable], [Iterator], [time manipulation](time.md)
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- Some samples: [combinatorics](samples/combinatorics.lyng.md), national vars and loops: [сумма ряда](samples/сумма_ряда.lyng.md). More at [samples folder](samples)
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- Some samples: [combinatorics](samples/combinatorics.lyng.md), national vars and
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loops: [сумма ряда](samples/сумма_ряда.lyng.md). More at [samples folder](samples)
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# Expressions
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@ -171,7 +172,8 @@ allow to improve code look and readability. There are borrowed from Kotlin:
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### let
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`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
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`value.let {}` passes to the block value as the single parameter (by default it is assigned to `it`) and return block's
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returned value. It is useful dealing with null or to
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get a snapshot of some externally varying value, or with `?.` to process nullable value in a safe manner:
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// this state is changed from parallel processes
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@ -465,7 +467,6 @@ after function call, it is treated as a last argument to the call, e.g.:
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assert( [11, 21, 31] == mapped)
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>>> void
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# Lists (aka arrays)
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Lyng has built-in mutable array class `List` with simple literals:
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@ -535,7 +536,8 @@ The simplest way to concatenate lists is using `+` and `+=`:
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void
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>>> void
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***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:
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***Important note***: the pitfall of using `+=` is that you can't append in [Iterable] instance as an object: it will
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always add all its contents. Use `list.add` to add a single iterable instance:
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var list = [1, 2]
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val other = [3, 4]
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@ -563,7 +565,6 @@ Use `list.add` to avoid confusion:
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assert( list == [1, 2, [3, 4], (10..12)])
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>>> void
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To add elements to the list:
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val x = [1,2]
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@ -596,7 +597,6 @@ Using splat arguments can simplify inserting list in list:
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x
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>>> [1, 0, 100, 0, 2, 3]
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Note that to add to the end you still need to use `add` or positive index of the after-last element:
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val x = [1,2,3]
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@ -742,7 +742,9 @@ Also, you can check the type too:
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#### Contains:
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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.
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You can thest that _when expression_ is _contained_, or not contained, in some object using `in container` and
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`!in container`. The container is any object that provides `contains` method, otherwise the runtime exception will be
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thrown.
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Typical builtin types that are containers (e.g. support `conain`):
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@ -758,7 +760,8 @@ Typical builtin types that are containers (e.g. support `conain`):
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: Iterable is not the container as it can be infinite
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(2)
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: 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:
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: Depending on the inclusivity and open/closed range parameters. BE careful here: String range is allowed, but it is
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usually not what you expect of it:
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assert( "more" in "a".."z") // string range ok
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assert( 'x' !in "a".."z") // char in string range: probably error
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@ -767,7 +770,9 @@ Typical builtin types that are containers (e.g. support `conain`):
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>>> void
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(3)
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: `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).
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: `String` also can provide array of characters directly with `str.characters()`, which is [Iterable] and [Array].
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String itself is not iterable as otherwise it will interfere when adding strigns to lists (it will add _characters_ it
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it would be iterable).
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So we recommend not to mix characters and string ranges; use `ch in str` that works
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as expected:
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@ -845,7 +850,8 @@ We can skip the rest of the loop and restart it, as usual, with `continue` opera
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"found even numbers: " + countEven
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>>> "found even numbers: 5"
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`continue` can't "return" anything: it just restarts the loop. It can use labeled loops to restart outer ones (we intentionally avoid using for loops here):
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`continue` can't "return" anything: it just restarts the loop. It can use labeled loops to restart outer ones (we
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intentionally avoid using for loops here):
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var count = 0
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var total = 0
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@ -891,21 +897,22 @@ test function (remember function return it's last expression result):
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```mermaid
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flowchart TD
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S((start)) --> Cond{check}
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Cond--false, no else--->V((void))
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Cond--true-->E(["last = loop_body()" ])
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E--break value---->BV((value))
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E--> Check2{check}
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E--break---->V
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Check2 --false-->E
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Check2 --true, no else--->L((last))
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Check2 --true, else-->Else(["else_clause()"])
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Cond--false, else--->Else
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Cond -- false, no else ---> V((void))
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Cond -- true --> E(["last = loop_body()"])
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E -- break value ----> BV((value))
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E --> Check2{check}
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E -- break ----> V
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Check2 -- false --> E
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Check2 -- true, no else ---> L((last))
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Check2 -- true, else --> Else(["else_clause()"])
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Cond -- false, else ---> Else
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Else --> Ele4$nr((else))
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```
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So the returned value, as seen from diagram could be one of:
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- `void`, if the loop was not executed, e.g. `condition` was initially false, and there was no `else` clause, or if the empty break was executed.
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- `void`, if the loop was not executed, e.g. `condition` was initially false, and there was no `else` clause, or if the
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empty break was executed.
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- value returned from `break value' statement
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- value returned from the `else` clause, of the loop was not broken
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- value returned from the last execution of loop body, if there was no `break` and no `else` clause.
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@ -929,7 +936,8 @@ available in the condition:
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} while( continueLoop )
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>>> "OK"
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This is sometimes convenient when condition is complex and has to be calculated inside the loop body. Notice the value returning by the loop:
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This is sometimes convenient when condition is complex and has to be calculated inside the loop body. Notice the value
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returning by the loop:
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fun readLine() { "done: result" }
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val result = do {
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@ -940,7 +948,6 @@ This is sometimes convenient when condition is complex and has to be calculated
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Suppose readLine() here reads some stream of lines.
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## For loops
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For loop are intended to traverse collections, and all other objects that supports
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@ -983,7 +990,8 @@ We can use labels too:
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# Exception handling
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Very much like in Kotlin. Try block returns its body block result, if no exception was cauht, or the result from the catch block that caught the exception:
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Very much like in Kotlin. Try block returns its body block result, if no exception was cauht, or the result from the
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catch block that caught the exception:
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var error = "not caught"
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var finallyCaught = false
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@ -1036,7 +1044,6 @@ many more.
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- see [exception handling](exceptions_handling.md) for detailed exceptions tutorial and reference.
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# Self-assignments in expression
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There are auto-increments and auto-decrements:
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@ -1159,7 +1166,6 @@ Are the same as in string literals with little difference:
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| code | Int | Unicode code for the character |
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| | | |
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## String details
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Strings are arrays of Unicode characters. It can be indexed, and indexing will
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@ -1187,7 +1193,10 @@ To format a string use sprintf-style modifiers like:
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assertEquals( "hello :11 ", "%-6s:%-6d"(a, b) )
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>>> void
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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.
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List of format specifiers closely resembles C sprintf() one.
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See [format specifiers](https://github.com/sergeych/mp_stools?tab=readme-ov-file#sprintf-syntax-summary), this is doe
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using [mp_stools kotlin multiplatform library](https://github.com/sergeych/mp_stools). Currently supported Lyng types
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are `String`, `Int`, `Real`, `Bool`, the rest are displayed using their `toString()` representation.
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This list will be extended.
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@ -1219,7 +1228,7 @@ Concatenation is a `+`: `"hello " + name` works as expected. No confusion.
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Typical set of String functions includes:
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| fun/prop | description / notes |
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|-------------------|------------------------------------------------------------|
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|--------------------|------------------------------------------------------------|
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| lower() | change case to unicode upper |
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| upper() | change case to unicode lower |
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| startsWith(prefix) | true if starts with a prefix |
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@ -1242,9 +1251,6 @@ Typical set of String functions includes:
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(1)
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: List is mutable therefore a new copy is created on each call.
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### Literals
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String literal could be multiline:
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@ -1259,9 +1265,17 @@ though multiline literals is yet work in progress.
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See [math functions](math.md). Other general purpose functions are:
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| name | description |
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|----------------------------------------------|----------------------------------------------------------|
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|--------------------------------------------|-----------------------------------------------------------|
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| assert(condition,message="assertion failed") | runtime code check. There will be an option to skip them |
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| println(args...) | Open for overriding, it prints to stdout. |
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| assertEquals(a,b) | |
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| assertNotEquals(a,b) | |
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| assertTrows { /* block */ } | |
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| check(condition, message=<default>) | throws IllegalStateException" of condition isn't met |
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| require(condition, message=<default>) | throws IllegalArgumentException" of condition isn't met |
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| println(args...) | Open for overriding, it prints to stdout with newline. |
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| print(args...) | Open for overriding, it prints to stdout without newline. |
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| flow {} | create flow sequence, see [parallelism] |
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| delay, launch, yield | see [parallelism] |
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# Built-in constants
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@ -1271,13 +1285,23 @@ See [math functions](math.md). Other general purpose functions are:
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| π | See [math](math.md) |
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[List]: List.md
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[Iterable]: Iterable.md
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[Iterator]: Iterator.md
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[Real]: Real.md
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[Range]: Range.md
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[String]: String.md
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[string formatting]: https://github.com/sergeych/mp_stools?tab=readme-ov-file#sprintf-syntax-summary
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[Set]: Set.md
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[Map]: Map.md
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[Buffer]: Buffer.md
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[parallelism]: parallelism.md
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@ -177,7 +177,7 @@ class Script(
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ObjVoid
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}
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addFn("traceScope") {
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this.trace(args.get(0)?.toString() ?: "")
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this.trace(args.getOrNull(0)?.toString() ?: "")
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ObjVoid
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}
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