fixed many bugs in closures processing also in flows

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

@@ -205,6 +205,20 @@ open class Scope(
         return "S[this=$thisObj $contents]"
     }
 
+    fun trace(text: String="") {
+        println("trace Scope: $text ------------------")
+        var p = this.parent
+        var level = 0
+        while (p != null) {
+            println("     parent#${++level}: $p")
+            println("     ( ${p.args.list} )")
+            p = p.parent
+        }
+        println("--------------------")
+        ObjVoid
+
+    }
+
     companion object {
 
         fun new(): Scope =

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

@@ -26,8 +26,15 @@ class Script(
 
     companion object {
 
-        private val rootScope: Scope = Scope(null).apply {
+        internal val rootScope: Scope = Scope(null).apply {
             ObjException.addExceptionsToContext(this)
+            addFn("print") {
+                for ((i, a) in args.withIndex()) {
+                    if (i > 0) print(' ' + a.asStr.value)
+                    else print(a.asStr.value)
+                }
+                ObjVoid
+            }
             addFn("println") {
                 for ((i, a) in args.withIndex()) {
                     if (i > 0) print(' ' + a.asStr.value)
@@ -153,16 +160,26 @@ class Script(
                 }
                 result ?: raiseError(ObjAssertionFailedException(this,"Expected exception but nothing was thrown"))
             }
-            addFn("traceScope") {
-                println("trace Scope: $this")
-                var p = this.parent
-                var level = 0
-                while (p != null) {
-                    println("     parent#${++level}: $p")
-                    p = p.parent
+            addFn("require") {
+                val condition = requiredArg<ObjBool>(0)
+                if( !condition.value ) {
+                    val message = args.list.getOrNull(1)?.toString() ?: "requirement not met"
+                    raiseIllegalArgument(message)
                 }
                 ObjVoid
             }
+            addFn("check") {
+                val condition = requiredArg<ObjBool>(0)
+                if( !condition.value ) {
+                    val message = args.list.getOrNull(1)?.toString() ?: "check failed"
+                    raiseIllegalState(message)
+                }
+                ObjVoid
+            }
+            addFn("traceScope") {
+                this.trace(args.get(0)?.toString() ?: "")
+                ObjVoid
+            }
 
             addVoidFn("delay") {
                 delay((this.args.firstAndOnly().toDouble()/1000.0).roundToLong())
@@ -204,7 +221,9 @@ class Script(
             }
 
             addFn("flow") {
-                ObjFlow(requireOnlyArg<Statement>())
+                // important is: current context contains closure often used in call;
+                // we'll need it for the producer
+                ObjFlow(requireOnlyArg<Statement>(), this)
             }
 
             val pi = ObjReal(PI)

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

@@ -7,9 +7,7 @@ import kotlinx.coroutines.channels.ReceiveChannel
 import kotlinx.coroutines.channels.SendChannel
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
-import net.sergeych.lyng.Scope
-import net.sergeych.lyng.ScriptFlowIsNoMoreCollected
-import net.sergeych.lyng.Statement
+import net.sergeych.lyng.*
 import net.sergeych.mp_tools.globalLaunch
 import kotlin.coroutines.cancellation.CancellationException
 
@@ -60,7 +58,7 @@ private fun createLyngFlowInput(scope: Scope, producer: Statement): ReceiveChann
     return channel
 }
 
-class ObjFlow(val producer: Statement) : Obj() {
+class ObjFlow(val producer: Statement, val scope: Scope) : Obj() {
 
     override val objClass = type
 
@@ -71,7 +69,8 @@ class ObjFlow(val producer: Statement) : Obj() {
             }
         }.apply {
             addFn("iterator") {
-                ObjFlowIterator(thisAs<ObjFlow>().producer)
+                val objFlow = thisAs<ObjFlow>()
+                ObjFlowIterator( statement { objFlow.producer.execute(ClosureScope(this,objFlow.scope)) } )
             }
         }
     }

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

@@ -111,6 +111,5 @@ val ObjIterable by lazy {
                     .not()
             )
         }
-
     }
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/stdlib_included/root_lyng.kt

@@ -0,0 +1,5 @@
+package net.sergeych.lyng.stdlib_included
+
+internal val rootLyng = """
+    
+""".trimIndent()

lynglib/src/commonMain/lyng/stdlib/Iterable.lyng

@@ -0,0 +1,16 @@
+
+fun Iterable.filter( predicate ) {
+    flow {
+        for( item in this )
+            if( predicate(item) )
+                emit(item)
+    }
+}
+
+fun Iterable.drop(n) {
+    require( n >= 0, "drop amount must be non-negative")
+    var count = 0
+    filter {
+        count++ < N
+    }
+}

lynglib/src/commonTest/kotlin/CoroutinesTest.kt

@@ -106,4 +106,67 @@ class TestCoroutines {
                 assertEquals( result, f.toList())
         """.trimIndent())
     }
+
+    @Test
+    fun testFlowClosures() = runTest {
+        eval("""
+            fun filter( a, b ) {
+                println("filter: %s, %s"(a,b))
+                flow {
+                    emit(a)
+                    emit(b)
+                }
+            }
+            
+            assertEquals( [5, 1], filter(5,1).toList() )
+            assertEquals( [2, 3], filter(2,3).toList() )
+            
+        """.trimIndent())
+    }
+
+
+    @Test
+    fun testFilterFlow() = runTest {
+        eval("""
+            fun filter( list, predicate ) {
+                val p = predicate
+                println("predicate "+predicate+" / "+p)
+                flow {
+                    // here p is captured only once and does not change!
+                    for( item in list ) {
+                        print("filter "+p+" "+item+": ")
+                        if( p(item) ) {
+                            println("OK")
+                            emit(item)
+                        }
+                        else println("NO")
+                    }
+                }
+            }
+            
+//            fun drop(i, n) {
+//                require( n >= 0, "drop amount must be non-negative")
+//                var count = 0
+//                println("drop %d"(n))
+//                filter(i) {
+//                    count++ >= n
+//                }
+//            }
+            
+            val src = (1..1).toList()
+            assertEquals( 1, filter(src) { true }.toList().size )
+            println("----------------------------------------------------------")
+            println("----------------------------------------------------------")
+            println("----------------------------------------------------------")
+            println("----------------------------------------------------------")
+            assertEquals( 0, filter(src) { false }.toList().size )
+//            assertEquals( 3, filter(src) { true }.size() ) 
+            
+//            assertEquals( [7,8], drop((1..8).toList(),6).toList())
+//            assertEquals( [1,3,5,7], filter((1..8).toList()) { 
+//                println("call2")
+//                it % 2 == 1 
+//            }.toList())
+        """.trimIndent())
+    }
 }