Fix JVM import caching and class/object bytecode dispatch

examples/fillspeed.lyng

@@ -0,0 +1,15 @@
+import lyng.time
+
+val n = 700_000
+
+fun tm<T>(block: ()->T): T {
+    val t = Instant()
+    block().also {
+        println("tm: ${Instant() - t}")
+    }
+}
+
+val x = tm { List.fill(n) { it * 10 + 1 } }
+val y = tm { List.fill(n, n + 10) { it * 10 + 1 } }
+tm { x.add(-1) }
+tm { y.add(-2) }

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

@@ -434,6 +434,57 @@ data class ArgsDeclaration(val params: List<Item>, val endTokenType: Token.Type)
         }
     }
 
+    fun supportsFastFrameBinding(arguments: Arguments): Boolean {
+        if (arguments.named.isNotEmpty() || arguments.tailBlockMode) return false
+        return params.none { it.isEllipsis || it.defaultValue != null }
+    }
+
+    fun assignToFrameFast(
+        scope: Scope,
+        arguments: Arguments = scope.args,
+        paramSlotPlan: Map<String, Int>,
+        frame: FrameAccess,
+        slotOffset: Int = 0
+    ) {
+        if (!supportsFastFrameBinding(arguments)) {
+            scope.raiseIllegalState("fast frame binding is not supported for this call shape")
+        }
+
+        fun slotFor(name: String): Int {
+            val full = paramSlotPlan[name] ?: scope.raiseIllegalState("parameter slot for '$name' is missing")
+            val slot = full - slotOffset
+            if (slot < 0) scope.raiseIllegalState("parameter slot for '$name' is out of range")
+            return slot
+        }
+
+        fun assign(slot: Int, value: Obj) {
+            when (value) {
+                is net.sergeych.lyng.obj.ObjInt -> frame.setInt(slot, value.value)
+                is net.sergeych.lyng.obj.ObjReal -> frame.setReal(slot, value.value)
+                is net.sergeych.lyng.obj.ObjBool -> frame.setBool(slot, value.value)
+                else -> frame.setObj(slot, value)
+            }
+        }
+
+        if (arguments.list.size > params.size) {
+            scope.raiseIllegalArgument("expected ${params.size} arguments, got ${arguments.list.size}")
+        }
+        if (arguments.list.size < params.size) {
+            for (i in arguments.list.size until params.size) {
+                val a = params[i]
+                if (!a.type.isNullable) {
+                    scope.raiseIllegalArgument("expected ${params.size} arguments, got ${arguments.list.size}")
+                }
+            }
+        }
+
+        for (i in params.indices) {
+            val slot = slotFor(params[i].name)
+            val value = if (i < arguments.list.size) arguments.list[i] else ObjNull
+            assign(slot, value.byValueCopy())
+        }
+    }
+
     /**
      * Single argument declaration descriptor.
      *

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

@@ -16,4 +16,12 @@
 
 package net.sergeych.lyng
 
-interface BytecodeCallable
+import net.sergeych.lyng.obj.Obj
+
+interface BytecodeCallable {
+    fun callOnFast(scope: Scope): Obj? = null
+}
+
+interface BytecodeArgCallable {
+    fun callWithArgsFast(scope: Scope, args: Arguments): Obj? = null
+}

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

@@ -28,6 +28,7 @@ internal suspend fun executeBytecodeWithSeed(scope: Scope, stmt: Statement, labe
         else -> null
     } ?: scope.raiseIllegalState("$label requires bytecode statement")
     scope.pos = bytecode.pos
+    bytecode.callOnFast(scope)?.let { return it }
     return CmdVm().execute(bytecode.bytecodeFunction(), scope, scope.args) { frame, _ ->
         seedFrameLocalsFromScope(frame, scope)
     }

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

@@ -20,5 +20,30 @@ package net.sergeych.lyng
  * Compile-time call metadata for known functions. Used to select lambda receiver semantics.
  */
 data class CallSignature(
-    val tailBlockReceiverType: String? = null
+    val tailBlockReceiverType: String? = null,
-)
+    val inlineHigherOrder: HigherOrderInline? = null
+) {
+    data class HigherOrderInline(
+        val kind: Kind,
+        val result: ResultMode,
+        val argCount: Int = 1,
+        val lambdaArgIndex: Int = 0
+    )
+
+    enum class Kind {
+        UNARY_ARGUMENT,
+        RECEIVER,
+        ITERABLE,
+        MAP_GET_OR_PUT
+    }
+
+    enum class ResultMode {
+        BLOCK_RESULT,
+        RETURN_RECEIVER,
+        FOR_EACH,
+        MAP,
+        FILTER,
+        MAP_NOT_NULL,
+        ASSOCIATE_BY
+    }
+}

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

@@ -187,6 +187,7 @@ class Compiler(
     private val callableReturnTypeByScopeId: MutableMap<Int, MutableMap<Int, ObjClass>> = mutableMapOf()
     private val callableReturnTypeByName: MutableMap<String, ObjClass> = mutableMapOf()
     private val callableReturnTypeDeclByName: MutableMap<String, TypeDecl> = mutableMapOf()
+    private val callSignatureByName: MutableMap<String, CallSignature> = mutableMapOf()
     private val lambdaReturnTypeByRef: MutableMap<ObjRef, ObjClass> = mutableMapOf()
     private val exactLambdaRefByScopeId: MutableMap<Int, MutableMap<Int, LambdaFnRef>> = mutableMapOf()
     private val lambdaCaptureEntriesByRef: MutableMap<ValueFnRef, List<net.sergeych.lyng.bytecode.LambdaCaptureEntry>> =
@@ -265,6 +266,11 @@ class Compiler(
                     if (plan.slots.containsKey(name)) continue
                     declareSlotNameIn(plan, name, record.isMutable, record.type == ObjRecord.Type.Delegated)
                     scopeSeedNames.add(name)
+                    record.callSignature?.let { signature ->
+                        if (!callSignatureByName.containsKey(name)) {
+                            callSignatureByName[name] = signature
+                        }
+                    }
                     if (record.typeDecl != null && nameTypeDecl[name] == null) {
                         nameTypeDecl[name] = record.typeDecl
                         if (nameObjClass[name] == null) {
@@ -291,6 +297,11 @@ class Compiler(
                                     )
                                     scopeSeedNames.add(getterName)
                                 }
+                                record.callSignature?.let { signature ->
+                                    if (!callSignatureByName.containsKey(getterName)) {
+                                        callSignatureByName[getterName] = signature
+                                    }
+                                }
                                 val prop = record.value as? ObjProperty
                                 if (prop?.setter != null) {
                                     val setterName = extensionPropertySetterName(cls.className, name)
@@ -316,6 +327,11 @@ class Compiler(
                                     )
                                     scopeSeedNames.add(callableName)
                                 }
+                                record.callSignature?.let { signature ->
+                                    if (!callSignatureByName.containsKey(callableName)) {
+                                        callSignatureByName[callableName] = signature
+                                    }
+                                }
                             }
                         }
                     }
@@ -347,6 +363,11 @@ class Compiler(
                 record.type == ObjRecord.Type.Delegated
             )
             scopeSeedNames.add(name)
+            record.callSignature?.let { signature ->
+                if (!callSignatureByName.containsKey(name)) {
+                    callSignatureByName[name] = signature
+                }
+            }
             if (record.typeDecl != null && nameTypeDecl[name] == null) {
                 nameTypeDecl[name] = record.typeDecl
                 if (nameObjClass[name] == null) {
@@ -762,6 +783,29 @@ class Compiler(
             ?: importManager.rootScope.getLocalRecordDirect(name)?.callSignature
     }
 
+    private fun declaredCallSignature(name: String, extTypeName: String?, actualExtern: Boolean): CallSignature? {
+        val imported = if (actualExtern) {
+            importManager.rootScope.getLocalRecordDirect(name)?.callSignature
+        } else {
+            null
+        }
+        val inferred = when {
+            extTypeName == "Iterable" && name == "filter" -> CallSignature(
+                inlineHigherOrder = CallSignature.HigherOrderInline(
+                    kind = CallSignature.Kind.ITERABLE,
+                    result = CallSignature.ResultMode.FILTER
+                )
+            )
+            else -> null
+        }
+        return when {
+            imported == null -> inferred
+            inferred == null -> imported
+            imported.inlineHigherOrder != null -> imported
+            else -> imported.copy(inlineHigherOrder = inferred.inlineHigherOrder)
+        }
+    }
+
     internal data class MemberIds(val fieldId: Int?, val methodId: Int?)
 
     private fun resolveMemberIds(name: String, pos: Pos, qualifier: String? = null): MemberIds {
@@ -1429,6 +1473,11 @@ class Compiler(
     }
 
     private fun seedImportTypeMetadata(name: String, record: ObjRecord) {
+        record.callSignature?.let { signature ->
+            if (!callSignatureByName.containsKey(name)) {
+                callSignatureByName[name] = signature
+            }
+        }
         if (record.typeDecl != null && nameTypeDecl[name] == null) {
             nameTypeDecl[name] = record.typeDecl
         }
@@ -1899,11 +1948,12 @@ class Compiler(
                         slotTypeDeclByScopeId = slotTypeDeclByScopeId,
                         knownNameObjClass = knownClassMapForBytecode(),
                         knownClassNames = knownClassNamesForBytecode(),
-                        knownObjectNames = objectDeclNames,
+                        knownObjectNames = knownObjectNamesForBytecode(),
                         classFieldTypesByName = classFieldTypesByName,
                         enumEntriesByName = enumEntriesByName,
                         callableReturnTypeByScopeId = callableReturnTypeByScopeId,
                         callableReturnTypeByName = callableReturnTypeByName,
+                        callSignatureByName = callSignatureByName,
                         externBindingNames = externBindingNames,
                         preparedModuleBindingNames = importBindings.keys,
                         scopeRefPosByName = moduleReferencePosByName,
@@ -2227,6 +2277,23 @@ class Compiler(
         return result
     }
 
+    private fun knownObjectNamesForBytecode(): Set<String> {
+        val result = LinkedHashSet<String>()
+        fun addScope(scope: Scope?) {
+            if (scope == null) return
+            for ((name, rec) in scope.objects) {
+                if (rec.value is ObjInstance) result.add(name)
+            }
+        }
+        addScope(seedScope)
+        addScope(importManager.rootScope)
+        for (module in importedModules) {
+            addScope(module.scope)
+        }
+        result.addAll(objectDeclNames)
+        return result
+    }
+
     private fun wrapBytecode(stmt: Statement): Statement {
         if (codeContexts.lastOrNull() is CodeContext.Module) return stmt
         if (codeContexts.lastOrNull() is CodeContext.ClassBody) return stmt
@@ -2255,11 +2322,12 @@ class Compiler(
             slotTypeDeclByScopeId = slotTypeDeclByScopeId,
             knownNameObjClass = knownClassMapForBytecode(),
             knownClassNames = knownClassNamesForBytecode(),
-            knownObjectNames = objectDeclNames,
+            knownObjectNames = knownObjectNamesForBytecode(),
             classFieldTypesByName = classFieldTypesByName,
             enumEntriesByName = enumEntriesByName,
             callableReturnTypeByScopeId = callableReturnTypeByScopeId,
             callableReturnTypeByName = callableReturnTypeByName,
+            callSignatureByName = callSignatureByName,
             externCallableNames = externCallableNames,
             externBindingNames = externBindingNames,
             preparedModuleBindingNames = importBindings.keys,
@@ -2289,11 +2357,12 @@ class Compiler(
             slotTypeDeclByScopeId = slotTypeDeclByScopeId,
             knownNameObjClass = knownClassMapForBytecode(),
             knownClassNames = knownClassNamesForBytecode(),
-            knownObjectNames = objectDeclNames,
+            knownObjectNames = knownObjectNamesForBytecode(),
             classFieldTypesByName = classFieldTypesByName,
             enumEntriesByName = enumEntriesByName,
             callableReturnTypeByScopeId = callableReturnTypeByScopeId,
             callableReturnTypeByName = callableReturnTypeByName,
+            callSignatureByName = callSignatureByName,
             externCallableNames = externCallableNames,
             externBindingNames = externBindingNames,
             preparedModuleBindingNames = importBindings.keys,
@@ -2348,11 +2417,12 @@ class Compiler(
             slotTypeDeclByScopeId = slotTypeDeclByScopeId,
             knownNameObjClass = knownNames,
             knownClassNames = knownClassNamesForBytecode(),
-            knownObjectNames = objectDeclNames,
+            knownObjectNames = knownObjectNamesForBytecode(),
             classFieldTypesByName = classFieldTypesByName,
             enumEntriesByName = enumEntriesByName,
             callableReturnTypeByScopeId = callableReturnTypeByScopeId,
             callableReturnTypeByName = callableReturnTypeByName,
+            callSignatureByName = callSignatureByName,
             externCallableNames = externCallableNames,
             externBindingNames = externBindingNames,
             preparedModuleBindingNames = importBindings.keys,
@@ -3545,14 +3615,90 @@ class Compiler(
         }
         val bytecodeFn = (fnStatements as? BytecodeStatement)?.bytecodeFunction()
         val inlineBodyRef = argsDeclaration?.let { null } ?: extractInlineLambdaBodyRef(body)
+        val supportsDirectInvokeFastPath = bytecodeFn != null &&
+            bytecodeFn.scopeSlotCount == 0 &&
+            expectedReceiverType == null &&
+            !wrapAsExtensionCallable &&
+            !containsDelegatedRefs(body)
         val ref = LambdaFnRef(
             valueFn = { closureScope ->
             val captureRecords = closureScope.captureRecords
-            val stmt = object : Statement(), BytecodeBodyProvider {
+            val stmt = object : Statement(), BytecodeBodyProvider, BytecodeCallable {
                 override val pos: Pos = fnStatements.pos
 
                 override fun bytecodeBody(): BytecodeStatement? = fnStatements as? BytecodeStatement
 
+                override fun callOnFast(scope: Scope): Obj? {
+                    val context = scope.applyClosureForBytecode(closureScope, preferredThisType = expectedReceiverType).also {
+                        it.args = scope.args
+                    }
+                    if (captureSlots.isNotEmpty()) {
+                        if (captureRecords != null) {
+                            context.captureRecords = captureRecords
+                            context.captureNames = captureSlots.map { it.name }
+                        } else {
+                            val resolvedRecords = ArrayList<ObjRecord>(captureSlots.size)
+                            val resolvedNames = ArrayList<String>(captureSlots.size)
+                            for (capture in captureSlots) {
+                                val rec = resolveStableCaptureRecord(
+                                    closureScope,
+                                    capture.name,
+                                    context.currentClassCtx
+                                ) ?: closureScope.raiseSymbolNotFound("symbol ${capture.name} not found")
+                                resolvedRecords.add(freezeImmutableCaptureRecord(rec))
+                                resolvedNames.add(capture.name)
+                            }
+                            context.captureRecords = resolvedRecords
+                            context.captureNames = resolvedNames
+                        }
+                    }
+                    val bytecodeBody = fnStatements as? BytecodeStatement ?: return null
+                    val bytecodeFn = bytecodeBody.bytecodeFunction()
+                    if (!supportsDirectInvokeFastPath || !bytecodeFn.fastOnly) return null
+                    val fastPreboundNames = if (argsDeclaration == null) {
+                        setOf("it")
+                    } else {
+                        argsDeclaration.params.mapTo(LinkedHashSet()) { it.name }
+                    }
+                    val declaredNames = bytecodeFn.constants
+                        .mapNotNull { it as? BytecodeConst.LocalDecl }
+                        .mapTo(mutableSetOf()) { it.name }
+                    if (!canFastSeedUndeclaredLocals(bytecodeFn, declaredNames, fastPreboundNames)) return null
+                    if (argsDeclaration != null && !argsDeclaration.supportsFastFrameBinding(scope.args)) return null
+                    val slotPlan = bytecodeFn.localSlotPlanByName()
+                    val binder: (net.sergeych.lyng.bytecode.CmdFrame, Arguments) -> Unit = { frame, arguments ->
+                        if (argsDeclaration == null) {
+                            val l = arguments.list
+                            val itValue: Obj = when (l.size) {
+                                0 -> ObjVoid
+                                1 -> l[0]
+                                else -> ObjList(l.toMutableList())
+                            }
+                            val itSlot = slotPlan["it"]
+                            if (itSlot != null) {
+                                when (itValue) {
+                                    is ObjInt -> frame.frame.setInt(itSlot, itValue.value)
+                                    is ObjReal -> frame.frame.setReal(itSlot, itValue.value)
+                                    is ObjBool -> frame.frame.setBool(itSlot, itValue.value)
+                                    else -> frame.frame.setObj(itSlot, itValue)
+                                }
+                            }
+                        } else {
+                            argsDeclaration.assignToFrameFast(
+                                context,
+                                arguments,
+                                slotPlan,
+                                frame.frame
+                            )
+                        }
+                    }
+                    return try {
+                        net.sergeych.lyng.bytecode.CmdVm().executeFastOnlyNoSuspend(bytecodeFn, context, scope.args, binder)
+                    } catch (e: ReturnException) {
+                        if (e.label == null || returnLabels.contains(e.label)) e.result else throw e
+                    }
+                }
+
                 override suspend fun execute(scope: Scope): Obj {
                     val context = scope.applyClosureForBytecode(closureScope, preferredThisType = expectedReceiverType).also {
                         it.args = scope.args
@@ -3628,6 +3774,7 @@ class Compiler(
             captureEntries = captureEntries,
             inferredReturnClass = returnClass,
             inlineBodyRef = inlineBodyRef,
+            supportsDirectInvokeFastPath = supportsDirectInvokeFastPath,
             preferredThisType = expectedReceiverType,
             wrapAsExtensionCallable = wrapAsExtensionCallable,
             returnLabels = returnLabels,
@@ -9131,7 +9278,7 @@ class Compiler(
         val extensionWrapperName = extTypeName?.let { extensionCallableName(it, name) }
         val classCtx = codeContexts.asReversed().firstOrNull { it is CodeContext.ClassBody } as? CodeContext.ClassBody
         var memberMethodId = if (extTypeName == null) classCtx?.memberMethodIds?.get(name) else null
-        val externCallSignature = if (actualExtern) importManager.rootScope.getLocalRecordDirect(name)?.callSignature else null
+        val externCallSignature = declaredCallSignature(name, extTypeName, actualExtern)
 
         val declKind = if (parentContext is CodeContext.ClassBody) SymbolKind.MEMBER else SymbolKind.FUNCTION
         resolutionSink?.declareSymbol(name, declKind, isMutable = false, pos = nameStartPos, isOverride = isOverride)
@@ -9153,7 +9300,9 @@ class Compiler(
         }
         if (extensionWrapperName != null) {
             declareLocalName(extensionWrapperName, isMutable = false)
+            externCallSignature?.let { callSignatureByName[extensionWrapperName] = it }
         }
+        externCallSignature?.let { callSignatureByName[name] = it }
         if (actualExtern && declKind != SymbolKind.MEMBER) {
             externCallableNames.add(name)
         }
@@ -9436,9 +9585,8 @@ class Compiler(
             val fnBody = object : Statement(), BytecodeBodyProvider {
                 override val pos: Pos = start
                 override fun bytecodeBody(): BytecodeStatement? = fnStatements as? BytecodeStatement
-                override suspend fun execute(scope: Scope): Obj {
-                    scope.pos = start
 
+                override suspend fun execute(scope: Scope): Obj {
                     // restore closure where the function was defined, and making a copy of it
                     // for local space. If there is no closure, we are in, say, class context where
                     // the closure is in the class initialization and we needn't more:
@@ -9447,6 +9595,7 @@ class Compiler(
                             it.args = scope.args
                         }
                     } ?: scope
+                    context.pos = start
 
                     // Capacity hint: parameters + declared locals + small overhead
                     val capacityHint = paramNames.size + fnLocalDecls + 4

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

@@ -118,7 +118,14 @@ internal suspend fun executeFunctionDecl(
             scope.addExtension(
                 type,
                 spec.name,
-                ObjRecord(ObjUnset, isMutable = false, visibility = spec.visibility, declaringClass = null, type = ObjRecord.Type.Delegated).apply {
+                ObjRecord(
+                    ObjUnset,
+                    isMutable = false,
+                    visibility = spec.visibility,
+                    declaringClass = null,
+                    type = ObjRecord.Type.Delegated,
+                    callSignature = spec.externCallSignature
+                ).apply {
                     delegate = finalDelegate
                 }
             )
@@ -135,7 +142,8 @@ internal suspend fun executeFunctionDecl(
                 null,
                 spec.startPos,
                 isTransient = spec.isTransient,
-                type = ObjRecord.Type.Delegated
+                type = ObjRecord.Type.Delegated,
+                callSignature = spec.externCallSignature
             ).apply {
                 delegate = finalDelegate
             }
@@ -204,6 +212,7 @@ internal suspend fun executeFunctionDecl(
                 visibility = spec.visibility,
                 pos = spec.startPos,
                 type = ObjRecord.Type.Fun,
+                callSignature = spec.externCallSignature,
             )
         } else {
             scope.addExtension(
@@ -215,6 +224,7 @@ internal suspend fun executeFunctionDecl(
                     visibility = spec.visibility,
                     declaringClass = null,
                     type = ObjRecord.Type.Fun,
+                    callSignature = spec.externCallSignature,
                     typeDecl = spec.typeDecl
                 )
             )
@@ -227,6 +237,7 @@ internal suspend fun executeFunctionDecl(
             wrapper,
             spec.visibility,
             recordType = ObjRecord.Type.Fun,
+            callSignature = spec.externCallSignature,
             typeDecl = spec.typeDecl
         )
     } ?: run {
@@ -245,7 +256,8 @@ internal suspend fun executeFunctionDecl(
                 isOverride = spec.isOverride,
                 type = ObjRecord.Type.Fun,
                 methodId = spec.memberMethodId,
-                typeDecl = spec.typeDecl
+                typeDecl = spec.typeDecl,
+                callSignature = spec.externCallSignature
             )
             val memberValue = cls.members[spec.name]?.value ?: compiledFnBody
             scope.addItem(

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

@@ -66,7 +66,11 @@ internal class ScopeBridge(internal val scope: Scope) : ScopeFacade {
     override fun raiseIllegalState(message: String): Nothing = scope.raiseIllegalState(message)
     override fun raiseNotImplemented(what: String): Nothing = scope.raiseNotImplemented(what)
     override suspend fun call(callee: Obj, args: Arguments, newThisObj: Obj?): Obj {
-        return callee.callOn(scope.createChildScope(scope.pos, args = args, newThisObj = newThisObj))
+        if (newThisObj == null) {
+            (callee as? BytecodeArgCallable)?.callWithArgsFast(scope, args)?.let { return it }
+        }
+        val child = scope.createChildScope(scope.pos, args = args, newThisObj = newThisObj)
+        return (callee as? BytecodeCallable)?.callOnFast(child) ?: callee.callOn(child)
     }
     override suspend fun toStringOf(obj: Obj, forInspect: Boolean): ObjString = obj.toString(scope, forInspect)
     override suspend fun inspect(obj: Obj): String = obj.inspect(scope)

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

@@ -108,11 +108,7 @@ class Script(
             seedImportBindings(scope, seedScope)
         }
         if (moduleSlotPlan.isNotEmpty()) {
-            scope.applySlotPlan(moduleSlotPlan)
+            installModuleSlotPlan(scope)
-            for (name in moduleSlotPlan.keys) {
-                val record = scope.objects[name] ?: scope.localBindings[name] ?: continue
-                scope.updateSlotFor(name, record)
-            }
         }
     }
 
@@ -120,13 +116,27 @@ class Script(
         if (importBindings.isEmpty() && importedModules.isEmpty()) return
         seedImportBindings(scope, seedScope)
         if (moduleSlotPlan.isNotEmpty()) {
-            scope.applySlotPlan(moduleSlotPlan)
+            installModuleSlotPlan(scope)
+        }
+    }
+
+    private fun installModuleSlotPlan(scope: Scope) {
+        for ((name, index) in moduleSlotPlan) {
+            if (scope.getSlotIndexOf(name) != null) continue
+            if (scope.hasSlotPlanConflict(mapOf(name to index))) {
+                val record = scope.objects[name]
+                    ?: scope.localBindings[name]
+                    ?: ObjRecord(ObjUnset, isMutable = true)
+                scope.allocateSlotFor(name, record)
+            } else {
+                scope.applySlotPlan(mapOf(name to index))
+            }
+        }
         for (name in moduleSlotPlan.keys) {
             val record = scope.objects[name] ?: scope.localBindings[name] ?: continue
             scope.updateSlotFor(name, record)
         }
     }
-    }
 
     private suspend fun seedModuleLocals(
         frame: net.sergeych.lyng.bytecode.CmdFrame,

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeConst.kt

@@ -40,6 +40,7 @@ sealed class BytecodeConst {
         val captureNames: List<String>,
         val paramSlotPlan: Map<String, Int>,
         val argsDeclaration: ArgsDeclaration?,
+        val supportsDirectInvokeFastPath: Boolean,
         val preferredThisType: String?,
         val wrapAsExtensionCallable: Boolean,
         val returnLabels: Set<String>,

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeStatement.kt

@@ -23,19 +23,36 @@ import net.sergeych.lyng.obj.*
 class BytecodeStatement private constructor(
     val original: Statement,
     private val function: CmdFunction,
-) : Statement(original.isStaticConst, original.isConst, original.returnType) {
+) : Statement(original.isStaticConst, original.isConst, original.returnType), BytecodeCallable {
     override val pos: Pos = original.pos
 
+    private val declaredLocalNames: Set<String> by lazy(LazyThreadSafetyMode.NONE) {
+        function.constants
+            .mapNotNull { it as? BytecodeConst.LocalDecl }
+            .mapTo(mutableSetOf()) { it.name }
+    }
+
+    override fun callOnFast(scope: Scope): Obj? {
+        scope.pos = pos
+        if (!function.fastOnly) return null
+        if (!canFastSeedUndeclaredLocals(function, declaredLocalNames, emptySet())) return null
+        val binder: (CmdFrame, Arguments) -> Unit = { frame, _ ->
+            if (!trySeedFrameLocalsFromScopeFast(frame, scope)) {
+                scope.raiseIllegalState("fast local seeding is not available")
+            }
+        }
+        return CmdVm().executeFastOnlyNoSuspend(function, scope, scope.args, binder)
+    }
+
     override suspend fun execute(scope: Scope): Obj {
         scope.pos = pos
-        val declaredNames = function.constants
+        val fastResult = callOnFast(scope)
-            .mapNotNull { it as? BytecodeConst.LocalDecl }
+        if (fastResult != null) return fastResult
-            .mapTo(mutableSetOf()) { it.name }
         val binder: suspend (CmdFrame, Arguments) -> Unit = { frame, _ ->
             val localNames = frame.fn.localSlotNames
             for (i in localNames.indices) {
                 val name = localNames[i] ?: continue
-                if (declaredNames.contains(name)) continue
+                if (declaredLocalNames.contains(name)) continue
                 val slotType = frame.getLocalSlotTypeCode(i)
                 if (slotType != SlotType.UNKNOWN.code && slotType != SlotType.OBJ.code) {
                     continue
@@ -89,6 +106,7 @@ class BytecodeStatement private constructor(
             enumEntriesByName: Map<String, List<String>> = emptyMap(),
             callableReturnTypeByScopeId: Map<Int, Map<Int, ObjClass>> = emptyMap(),
             callableReturnTypeByName: Map<String, ObjClass> = emptyMap(),
+            callSignatureByName: Map<String, CallSignature> = emptyMap(),
             externCallableNames: Set<String> = emptySet(),
             externBindingNames: Set<String> = emptySet(),
             preparedModuleBindingNames: Set<String> = emptySet(),
@@ -129,6 +147,7 @@ class BytecodeStatement private constructor(
                 enumEntriesByName = enumEntriesByName,
                 callableReturnTypeByScopeId = callableReturnTypeByScopeId,
                 callableReturnTypeByName = callableReturnTypeByName,
+                callSignatureByName = callSignatureByName,
                 externCallableNames = externCallableNames,
                 externBindingNames = externBindingNames,
                 preparedModuleBindingNames = preparedModuleBindingNames,

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdBuilder.kt

@@ -112,6 +112,7 @@ class CmdBuilder {
             }
             cmds.add(createCmd(ins.op, operands, scopeSlotCount, localSlotCaptures))
         }
+        val cmdArray = cmds.toTypedArray()
         return CmdFunction(
             name = name,
             localCount = localCount,
@@ -128,8 +129,9 @@ class CmdBuilder {
             localSlotDelegated = localSlotDelegated,
             localSlotCaptures = localSlotCaptures,
             constants = constPool.toList(),
-            cmds = cmds.toTypedArray(),
+            cmds = cmdArray,
-            posByIp = posByInstr.toTypedArray()
+            posByIp = posByInstr.toTypedArray(),
+            fastOnly = computeFastOnlyBytecode(scopeSlotCount, cmdArray)
         )
     }
 
@@ -237,6 +239,10 @@ class CmdBuilder {
                 listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
             Opcode.LIST_IOTA_INT ->
                 listOf(OperandKind.SLOT, OperandKind.SLOT)
+            Opcode.LIST_NEW_INT_CAP ->
+                listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
+            Opcode.LIST_FILL_INT_CAP ->
+                listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
             Opcode.MAKE_RANGE ->
                 listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
             Opcode.LIST_LITERAL ->
@@ -842,6 +848,8 @@ class CmdBuilder {
             Opcode.LIST_NEW_INT -> CmdListNewInt(operands[0], operands[1])
             Opcode.LIST_FILL_INT -> CmdListFillInt(operands[0], operands[1], operands[2])
             Opcode.LIST_IOTA_INT -> CmdListIotaInt(operands[0], operands[1])
+            Opcode.LIST_NEW_INT_CAP -> CmdListNewIntCap(operands[0], operands[1], operands[2])
+            Opcode.LIST_FILL_INT_CAP -> CmdListFillIntCap(operands[0], operands[1], operands[2], operands[3])
             Opcode.LIST_LITERAL -> CmdListLiteral(operands[0], operands[1], operands[2], operands[3])
             Opcode.GET_MEMBER_SLOT -> CmdGetMemberSlot(operands[0], operands[1], operands[2], operands[3])
             Opcode.SET_MEMBER_SLOT -> CmdSetMemberSlot(operands[0], operands[1], operands[2], operands[3])

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdDisassembler.kt

@@ -498,6 +498,8 @@ object CmdDisassembler {
             is CmdListNewInt -> Opcode.LIST_NEW_INT to intArrayOf(cmd.sizeSlot, cmd.dst)
             is CmdListFillInt -> Opcode.LIST_FILL_INT to intArrayOf(cmd.sizeSlot, cmd.callableSlot, cmd.dst)
             is CmdListIotaInt -> Opcode.LIST_IOTA_INT to intArrayOf(cmd.sizeSlot, cmd.dst)
+            is CmdListNewIntCap -> Opcode.LIST_NEW_INT_CAP to intArrayOf(cmd.sizeSlot, cmd.capacitySlot, cmd.dst)
+            is CmdListFillIntCap -> Opcode.LIST_FILL_INT_CAP to intArrayOf(cmd.sizeSlot, cmd.capacitySlot, cmd.callableSlot, cmd.dst)
             is CmdListLiteral -> Opcode.LIST_LITERAL to intArrayOf(cmd.planId, cmd.baseSlot, cmd.count, cmd.dst)
             is CmdGetMemberSlot -> Opcode.GET_MEMBER_SLOT to intArrayOf(cmd.recvSlot, cmd.fieldId, cmd.methodId, cmd.dst)
             is CmdSetMemberSlot -> Opcode.SET_MEMBER_SLOT to intArrayOf(cmd.recvSlot, cmd.fieldId, cmd.methodId, cmd.valueSlot)
@@ -627,6 +629,10 @@ object CmdDisassembler {
                 listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
             Opcode.LIST_IOTA_INT ->
                 listOf(OperandKind.SLOT, OperandKind.SLOT)
+            Opcode.LIST_NEW_INT_CAP ->
+                listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
+            Opcode.LIST_FILL_INT_CAP ->
+                listOf(OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT, OperandKind.SLOT)
             Opcode.LIST_LITERAL ->
                 listOf(OperandKind.CONST, OperandKind.SLOT, OperandKind.COUNT, OperandKind.SLOT)
             Opcode.GET_MEMBER_SLOT ->

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdFunction.kt

@@ -35,6 +35,7 @@ data class CmdFunction(
     val constants: List<BytecodeConst>,
     val cmds: Array<Cmd>,
     val posByIp: Array<net.sergeych.lyng.Pos?>,
+    val fastOnly: Boolean = false,
 ) {
     init {
         require(scopeSlotIndices.size == scopeSlotCount) { "scopeSlotIndices size mismatch" }
@@ -71,3 +72,118 @@ data class CmdFunction(
     }
 
 }
+
+internal fun computeFastOnlyBytecode(scopeSlotCount: Int, cmds: Array<Cmd>): Boolean {
+    if (scopeSlotCount != 0) return false
+    return cmds.all(::supportsFastOnlyExecution)
+}
+
+private fun supportsFastOnlyExecution(cmd: Cmd): Boolean {
+    return when (cmd) {
+        is CmdMoveIntLocal,
+        is CmdMoveRealLocal,
+        is CmdMoveBoolLocal,
+        is CmdConstObj,
+        is CmdConstInt,
+        is CmdConstIntLocal,
+        is CmdConstReal,
+        is CmdConstBool,
+        is CmdConstNull,
+        is CmdUnboxIntObjLocal,
+        is CmdUnboxRealObjLocal,
+        is CmdIntToRealLocal,
+        is CmdRealToIntLocal,
+        is CmdBoolToIntLocal,
+        is CmdIntToBoolLocal,
+        is CmdAddIntLocal,
+        is CmdSubIntLocal,
+        is CmdMulIntLocal,
+        is CmdDivIntLocal,
+        is CmdModIntLocal,
+        is CmdNegIntLocal,
+        is CmdIncIntLocal,
+        is CmdDecIntLocal,
+        is CmdAddRealLocal,
+        is CmdSubRealLocal,
+        is CmdMulRealLocal,
+        is CmdDivRealLocal,
+        is CmdNegRealLocal,
+        is CmdAndIntLocal,
+        is CmdOrIntLocal,
+        is CmdXorIntLocal,
+        is CmdShlIntLocal,
+        is CmdShrIntLocal,
+        is CmdUshrIntLocal,
+        is CmdInvIntLocal,
+        is CmdCmpEqIntLocal,
+        is CmdCmpNeqIntLocal,
+        is CmdCmpLtIntLocal,
+        is CmdCmpLteIntLocal,
+        is CmdCmpGtIntLocal,
+        is CmdCmpGteIntLocal,
+        is CmdCmpEqRealLocal,
+        is CmdCmpNeqRealLocal,
+        is CmdCmpLtRealLocal,
+        is CmdCmpLteRealLocal,
+        is CmdCmpGtRealLocal,
+        is CmdCmpGteRealLocal,
+        is CmdCmpEqBoolLocal,
+        is CmdCmpNeqBoolLocal,
+        is CmdCmpEqIntRealLocal,
+        is CmdCmpEqRealIntLocal,
+        is CmdCmpLtIntRealLocal,
+        is CmdCmpLtRealIntLocal,
+        is CmdCmpLteIntRealLocal,
+        is CmdCmpLteRealIntLocal,
+        is CmdCmpGtIntRealLocal,
+        is CmdCmpGtRealIntLocal,
+        is CmdCmpGteIntRealLocal,
+        is CmdCmpGteRealIntLocal,
+        is CmdCmpNeqIntRealLocal,
+        is CmdCmpNeqRealIntLocal,
+        is CmdCmpEqStrLocal,
+        is CmdCmpNeqStrLocal,
+        is CmdCmpLtStrLocal,
+        is CmdCmpLteStrLocal,
+        is CmdCmpGtStrLocal,
+        is CmdCmpGteStrLocal,
+        is CmdCmpEqIntObjLocal,
+        is CmdCmpNeqIntObjLocal,
+        is CmdCmpLtIntObjLocal,
+        is CmdCmpLteIntObjLocal,
+        is CmdCmpGtIntObjLocal,
+        is CmdCmpGteIntObjLocal,
+        is CmdCmpEqRealObjLocal,
+        is CmdCmpNeqRealObjLocal,
+        is CmdCmpLtRealObjLocal,
+        is CmdCmpLteRealObjLocal,
+        is CmdCmpGtRealObjLocal,
+        is CmdCmpGteRealObjLocal,
+        is CmdAddIntObjLocal,
+        is CmdSubIntObjLocal,
+        is CmdMulIntObjLocal,
+        is CmdDivIntObjLocal,
+        is CmdModIntObjLocal,
+        is CmdAddRealObjLocal,
+        is CmdSubRealObjLocal,
+        is CmdMulRealObjLocal,
+        is CmdDivRealObjLocal,
+        is CmdModRealObjLocal,
+        is CmdNotBoolLocal,
+        is CmdAndBoolLocal,
+        is CmdOrBoolLocal,
+        is CmdJmp,
+        is CmdJmpIfTrueLocal,
+        is CmdJmpIfFalseLocal,
+        is CmdJmpIfEqIntLocal,
+        is CmdJmpIfNeqIntLocal,
+        is CmdJmpIfLtIntLocal,
+        is CmdJmpIfLteIntLocal,
+        is CmdJmpIfGtIntLocal,
+        is CmdJmpIfGteIntLocal,
+        is CmdRet,
+        is CmdRetVoid -> true
+
+        else -> false
+    }
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdRuntime.kt

@@ -57,6 +57,64 @@ class CmdVm {
     suspend fun execute(fn: CmdFunction, scope0: Scope, args: List<Obj>): Obj {
         return execute(fn, scope0, Arguments.from(args))
     }
+
+    fun executeFastOnlyNoSuspend(
+        fn: CmdFunction,
+        scope0: Scope,
+        args: Arguments,
+        binder: ((CmdFrame, Arguments) -> Unit)? = null
+    ): Obj {
+        require(fn.fastOnly) { "fast-only execution requested for non-fast function ${fn.name}" }
+        result = null
+        val frame = CmdFrame(this, fn, scope0, args.list)
+        frame.applyCaptureRecords()
+        binder?.invoke(frame, args)
+        val cmds = fn.cmds
+        try {
+            while (result == null) {
+                val cmd = cmds[frame.ip++]
+                if (!cmd.performFast(frame)) {
+                    error("fast-only command not supported: ${cmd::class.simpleName}")
+                }
+            }
+        } catch (e: Throwable) {
+            throw frame.normalizeThrowableFast(e)
+        }
+        return result ?: ObjVoid
+    }
+
+    suspend fun executeFastOnly(
+        fn: CmdFunction,
+        scope0: Scope,
+        args: Arguments,
+        binder: ((CmdFrame, Arguments) -> Unit)? = null
+    ): Obj {
+        require(fn.fastOnly) { "fast-only execution requested for non-fast function ${fn.name}" }
+        result = null
+        val frame = CmdFrame(this, fn, scope0, args.list)
+        frame.applyCaptureRecords()
+        binder?.invoke(frame, args)
+        val cmds = fn.cmds
+        while (true) {
+            try {
+                while (result == null) {
+                    val cmd = cmds[frame.ip++]
+                    if (!cmd.performFast(frame)) {
+                        error("fast-only command not supported: ${cmd::class.simpleName}")
+                    }
+                }
+                break
+            } catch (e: Throwable) {
+                val throwable = frame.normalizeThrowable(e)
+                if (!frame.handleException(throwable)) {
+                    frame.cancelIterators()
+                    throw throwable
+                }
+            }
+        }
+        frame.cancelIterators()
+        return result ?: ObjVoid
+    }
 }
 
 sealed class Cmd {
@@ -280,6 +338,11 @@ class CmdMakeRange(
 }
 
 class CmdConstNull(internal val dst: Int) : Cmd() {
+    override fun performFast(frame: CmdFrame): Boolean {
+        frame.setObj(dst, ObjNull)
+        return true
+    }
+
     override suspend fun perform(frame: CmdFrame) {
         frame.setObj(dst, ObjNull)
         return
@@ -2301,6 +2364,11 @@ class CmdJmpIfGteIntLocal(internal val a: Int, internal val b: Int, internal val
 }
 
 class CmdRet(internal val slot: Int) : Cmd() {
+    override fun performFast(frame: CmdFrame): Boolean {
+        frame.vm.result = frame.storedSlotObj(slot)
+        return true
+    }
+
     override suspend fun perform(frame: CmdFrame) {
         frame.vm.result = frame.slotToObj(slot)
         return
@@ -2322,6 +2390,11 @@ class CmdRetLabel(internal val labelId: Int, internal val slot: Int) : Cmd() {
 }
 
 class CmdRetVoid : Cmd() {
+    override fun performFast(frame: CmdFrame): Boolean {
+        frame.vm.result = ObjVoid
+        return true
+    }
+
     override suspend fun perform(frame: CmdFrame) {
         frame.vm.result = ObjVoid
         return
@@ -3217,10 +3290,21 @@ class CmdCallDirect(
                 frame.ensureScope().raiseIllegalState("bytecode runtime cannot call non-bytecode Statement")
             }
         }
-        val result = if (PerfFlags.SCOPE_POOL) {
+        val directFastResult = (callee as? BytecodeArgCallable)?.callWithArgsFast(frame.ensureScope(), args)
-            frame.ensureScope().withChildFrame(args) { child -> callee.callOn(child) }
+        val result = if (directFastResult != null) {
+            directFastResult
+        } else if (PerfFlags.SCOPE_POOL) {
+            frame.ensureScope().withChildFrame(args) { child ->
+                (callee as? BytecodeCallable)?.callOnFast(child) ?: callee.callOn(child)
+            }
         } else {
-            callee.callOn(frame.ensureScope().createChildScope(frame.ensureScope().pos, args = args))
+            val scope = frame.ensureScope()
+            if (callee is BytecodeLambdaCallable && callee.supportsDirectInvokeFastPath()) {
+                callee.invokeWithArgsFast(scope, args) ?: callee.invokeWithArgs(scope, args)
+            } else {
+                val child = scope.createChildScope(scope.pos, args = args)
+                (callee as? BytecodeCallable)?.callOnFast(child) ?: callee.callOn(child)
+            }
         }
         frame.storeObjResult(dst, result)
         return
@@ -3247,18 +3331,28 @@ class CmdCallSlot(
             frame.ensureScope().raiseUnset(message)
         }
         val args = frame.buildArguments(argBase, argCount)
-        val canPool = PerfFlags.SCOPE_POOL && callee !is Statement
-        val result = if (canPool) {
-            frame.ensureScope().withChildFrame(args) { child -> callee.callOn(child) }
-        } else {
         val scope = frame.ensureScope()
+        val directFastResult = (callee as? BytecodeArgCallable)?.callWithArgsFast(scope, args)
+        val canPool = PerfFlags.SCOPE_POOL && callee !is Statement
+        val result = if (directFastResult != null) {
+            directFastResult
+        } else if (canPool) {
+            frame.ensureScope().withChildFrame(args) { child ->
+                (callee as? BytecodeCallable)?.callOnFast(child) ?: callee.callOn(child)
+            }
+        } else {
             if (callee is Statement) {
                 val bytecodeBody = (callee as? BytecodeBodyProvider)?.bytecodeBody()
                 if (callee !is BytecodeStatement && callee !is BytecodeCallable && bytecodeBody == null) {
                     scope.raiseIllegalState("bytecode runtime cannot call non-bytecode Statement")
                 }
             }
-            callee.callOn(scope.createChildScope(scope.pos, args = args))
+            if (callee is BytecodeLambdaCallable && callee.supportsDirectInvokeFastPath()) {
+                callee.invokeWithArgsFast(scope, args) ?: callee.invokeWithArgs(scope, args)
+            } else {
+                val child = scope.createChildScope(scope.pos, args = args)
+                (callee as? BytecodeCallable)?.callOnFast(child) ?: callee.callOn(child)
+            }
         }
         frame.storeObjResult(dst, result)
         return
@@ -3341,10 +3435,53 @@ class CmdListFillInt(
         val scope = frame.ensureScope()
         val result = ObjList(LongArray(size))
         for (i in 0 until size) {
+            val args = Arguments(ObjInt.of(i.toLong()))
             val value = if (callable is BytecodeLambdaCallable && callable.supportsImplicitIntFillFastPath()) {
-                callable.invokeImplicitIntArg(scope, i.toLong())
+                callable.invokeImplicitIntArgFast(scope, i.toLong()) ?: callable.invokeImplicitIntArg(scope, i.toLong())
+            } else if (callable is BytecodeArgCallable) {
+                callable.callWithArgsFast(scope, args) ?: run {
+                    val child = scope.createChildScope(scope.pos, args = args)
+                    (callable as? BytecodeCallable)?.callOnFast(child) ?: callable.callOn(child)
+                }
             } else {
-                callable.callOn(scope.createChildScope(scope.pos, args = Arguments(ObjInt.of(i.toLong()))))
+                val child = scope.createChildScope(scope.pos, args = args)
+                (callable as? BytecodeCallable)?.callOnFast(child) ?: callable.callOn(child)
+            }
+            val intValue = (value as? ObjInt)?.value ?: scope.raiseClassCastError("expected Int fill result")
+            result.setIntAtFast(i, intValue)
+        }
+        frame.storeObjResult(dst, result)
+        return
+    }
+}
+
+class CmdListFillIntCap(
+    internal val sizeSlot: Int,
+    internal val capacitySlot: Int,
+    internal val callableSlot: Int,
+    internal val dst: Int,
+) : Cmd() {
+    override suspend fun perform(frame: CmdFrame) {
+        val size = frame.getInt(sizeSlot).toInt()
+        if (size < 0) frame.ensureScope().raiseIllegalArgument("list size must be non-negative")
+        val capacity = frame.getInt(capacitySlot).toInt()
+        val actualCapacity = maxOf(size, capacity)
+        if (actualCapacity < 0) frame.ensureScope().raiseIllegalArgument("list capacity must be non-negative")
+        val callable = frame.storedSlotObj(callableSlot)
+        val scope = frame.ensureScope()
+        val result = ObjList(LongArray(actualCapacity), size)
+        for (i in 0 until size) {
+            val args = Arguments(ObjInt.of(i.toLong()))
+            val value = if (callable is BytecodeLambdaCallable && callable.supportsImplicitIntFillFastPath()) {
+                callable.invokeImplicitIntArgFast(scope, i.toLong()) ?: callable.invokeImplicitIntArg(scope, i.toLong())
+            } else if (callable is BytecodeArgCallable) {
+                callable.callWithArgsFast(scope, args) ?: run {
+                    val child = scope.createChildScope(scope.pos, args = args)
+                    (callable as? BytecodeCallable)?.callOnFast(child) ?: callable.callOn(child)
+                }
+            } else {
+                val child = scope.createChildScope(scope.pos, args = args)
+                (callable as? BytecodeCallable)?.callOnFast(child) ?: callable.callOn(child)
             }
             val intValue = (value as? ObjInt)?.value ?: scope.raiseClassCastError("expected Int fill result")
             result.setIntAtFast(i, intValue)
@@ -3758,6 +3895,22 @@ class CmdListNewInt(
     }
 }
 
+class CmdListNewIntCap(
+    internal val sizeSlot: Int,
+    internal val capacitySlot: Int,
+    internal val dst: Int,
+) : Cmd() {
+    override suspend fun perform(frame: CmdFrame) {
+        val size = frame.getInt(sizeSlot).toInt()
+        if (size < 0) frame.ensureScope().raiseIllegalArgument("list size must be non-negative")
+        val capacity = frame.getInt(capacitySlot).toInt()
+        val actualCapacity = maxOf(size, capacity)
+        if (actualCapacity < 0) frame.ensureScope().raiseIllegalArgument("list capacity must be non-negative")
+        frame.storeObjResult(dst, ObjList(LongArray(actualCapacity), size))
+        return
+    }
+}
+
 class CmdGetIndex(
     internal val targetSlot: Int,
     internal val indexSlot: Int,
@@ -3862,6 +4015,7 @@ class CmdMakeLambda(internal val id: Int, internal val dst: Int) : Cmd() {
             captureNames = lambdaConst.captureNames,
             paramSlotPlan = lambdaConst.paramSlotPlan,
             argsDeclaration = lambdaConst.argsDeclaration,
+            supportsDirectInvokeFastPath = lambdaConst.supportsDirectInvokeFastPath,
             preferredThisType = lambdaConst.preferredThisType,
             returnLabels = lambdaConst.returnLabels,
             pos = lambdaConst.pos
@@ -3883,10 +4037,18 @@ class BytecodeLambdaCallable(
     private val captureNames: List<String>,
     private val paramSlotPlan: Map<String, Int>,
     private val argsDeclaration: ArgsDeclaration?,
+    private val supportsDirectInvokeFastPath: Boolean,
     private val preferredThisType: String?,
     private val returnLabels: Set<String>,
     override val pos: Pos,
-) : Statement(), BytecodeCallable {
+) : Statement(), BytecodeCallable, BytecodeArgCallable {
+    private val slotPlanByName: Map<String, Int> by lazy(LazyThreadSafetyMode.NONE) { fn.localSlotPlanByName() }
+    private val declaredLocalNames: Set<String> by lazy(LazyThreadSafetyMode.NONE) {
+        fn.constants
+            .mapNotNull { it as? BytecodeConst.LocalDecl }
+            .mapTo(mutableSetOf()) { it.name }
+    }
+
     private fun freezeRecord(record: ObjRecord): ObjRecord {
         if (record.isMutable) return record
         val raw = record.value as Obj?
@@ -3918,6 +4080,7 @@ class BytecodeLambdaCallable(
             captureNames = captureNames,
             paramSlotPlan = paramSlotPlan,
             argsDeclaration = argsDeclaration,
+            supportsDirectInvokeFastPath = supportsDirectInvokeFastPath,
             preferredThisType = preferredThisType,
             returnLabels = returnLabels,
             pos = pos
@@ -3934,6 +4097,7 @@ class BytecodeLambdaCallable(
             captureNames = captureNames,
             paramSlotPlan = paramSlotPlan,
             argsDeclaration = argsDeclaration,
+            supportsDirectInvokeFastPath = supportsDirectInvokeFastPath,
             preferredThisType = preferredThisType,
             returnLabels = returnLabels,
             pos = pos
@@ -3942,32 +4106,29 @@ class BytecodeLambdaCallable(
 
     fun supportsImplicitIntFillFastPath(): Boolean = argsDeclaration == null
 
-    suspend fun invokeImplicitIntArg(scope: Scope, arg: Long): Obj {
+    fun supportsDirectInvokeFastPath(): Boolean = supportsDirectInvokeFastPath
-        val context = scope.applyClosureForBytecode(closureScope, preferredThisType).also {
+
-            it.args = Arguments.EMPTY
+    private val fastPreboundLocalNames: Set<String> by lazy(LazyThreadSafetyMode.NONE) {
-        }
+        if (argsDeclaration == null) {
-        if (captureRecords != null) {
+            setOf("it")
-            context.captureRecords = captureRecords
+        } else {
-            context.captureNames = captureNames
+            argsDeclaration.params.mapTo(LinkedHashSet()) { it.name }
-        } else if (captureNames.isNotEmpty()) {
-            closureScope.raiseIllegalState("bytecode lambda capture records missing")
-        }
-        val binder: suspend (CmdFrame, Arguments) -> Unit = { frame, _ ->
-            paramSlotPlan["it"]?.let { itSlot ->
-                frame.frame.setInt(itSlot, arg)
-            }
-        }
-        return try {
-            CmdVm().execute(fn, context, Arguments.EMPTY, binder)
-        } catch (e: ReturnException) {
-            if (e.label == null || returnLabels.contains(e.label)) e.result
-            else throw e
         }
     }
 
-    override suspend fun execute(scope: Scope): Obj {
+    private val supportsFastUndeclaredLocalInit: Boolean by lazy(LazyThreadSafetyMode.NONE) {
-        val context = scope.applyClosureForBytecode(closureScope, preferredThisType).also {
+        canFastSeedUndeclaredLocals(fn, declaredLocalNames, fastPreboundLocalNames)
-            it.args = scope.args
+    }
+
+    private fun supportsFastOnlyVm(arguments: Arguments): Boolean {
+        if (!supportsDirectInvokeFastPath || !fn.fastOnly) return false
+        if (!supportsFastUndeclaredLocalInit) return false
+        return argsDeclaration == null || argsDeclaration.supportsFastFrameBinding(arguments)
+    }
+
+    private fun buildContext(callScope: Scope, args: Arguments): Scope {
+        val context = callScope.applyClosureForBytecode(closureScope, preferredThisType).also {
+            it.args = args
         }
         if (captureRecords != null) {
             context.captureRecords = captureRecords
@@ -3975,17 +4136,10 @@ class BytecodeLambdaCallable(
         } else if (captureNames.isNotEmpty()) {
             closureScope.raiseIllegalState("bytecode lambda capture records missing")
         }
-        if (argsDeclaration == null) {
+        return context
-            // Bound in the bytecode entry binder.
-        } else {
-            // args bound into frame slots in the bytecode entry binder
     }
-        return try {
+
-            val declaredNames = fn.constants
+    private fun bindArgumentsFast(frame: CmdFrame, context: Scope, arguments: Arguments) {
-                .mapNotNull { it as? BytecodeConst.LocalDecl }
-                .mapTo(mutableSetOf()) { it.name }
-            val binder: suspend (CmdFrame, Arguments) -> Unit = { frame, arguments ->
-                val slotPlan = fn.localSlotPlanByName()
         if (argsDeclaration == null) {
             val l = arguments.list
             val itValue: Obj = when (l.size) {
@@ -3993,7 +4147,7 @@ class BytecodeLambdaCallable(
                 1 -> l[0]
                 else -> ObjList(l.toMutableList())
             }
-                    val itSlot = slotPlan["it"]
+            val itSlot = slotPlanByName["it"]
             if (itSlot != null) {
                 when (itValue) {
                     is ObjInt -> frame.frame.setInt(itSlot, itValue.value)
@@ -4003,17 +4157,33 @@ class BytecodeLambdaCallable(
                 }
             }
         } else {
-                    argsDeclaration.assignToFrame(
+            argsDeclaration.assignToFrameFast(
                 context,
                 arguments,
-                        slotPlan,
+                slotPlanByName,
                 frame.frame
             )
         }
+    }
+
+    private suspend fun bindArguments(frame: CmdFrame, context: Scope, arguments: Arguments) {
+        if (argsDeclaration == null) {
+            bindArgumentsFast(frame, context, arguments)
+        } else {
+            argsDeclaration.assignToFrame(
+                context,
+                arguments,
+                slotPlanByName,
+                frame.frame
+            )
+        }
+    }
+
+    private suspend fun seedUndeclaredLocals(frame: CmdFrame, context: Scope) {
         val localNames = frame.fn.localSlotNames
         for (i in localNames.indices) {
             val name = localNames[i] ?: continue
-                    if (declaredNames.contains(name)) continue
+            if (declaredLocalNames.contains(name)) continue
             val slotType = frame.getLocalSlotTypeCode(i)
             if (slotType != SlotType.UNKNOWN.code && slotType != SlotType.OBJ.code) {
                 continue
@@ -4039,11 +4209,88 @@ class BytecodeLambdaCallable(
             frame.frame.setObj(i, value)
         }
     }
-            CmdVm().execute(fn, context, scope.args, binder)
+
+    suspend fun invokeImplicitIntArg(scope: Scope, arg: Long): Obj {
+        val context = buildContext(scope, Arguments.EMPTY)
+        val fastBinder: (CmdFrame, Arguments) -> Unit = { frame, _ ->
+            slotPlanByName["it"]?.let { itSlot ->
+                frame.frame.setInt(itSlot, arg)
+            }
+        }
+        return try {
+            val vm = CmdVm()
+            if (supportsFastOnlyVm(Arguments.EMPTY)) {
+                vm.executeFastOnly(fn, context, Arguments.EMPTY, fastBinder)
+            } else {
+                val binder: suspend (CmdFrame, Arguments) -> Unit = { frame, _ ->
+                    slotPlanByName["it"]?.let { itSlot ->
+                        frame.frame.setInt(itSlot, arg)
+                    }
+                }
+                vm.execute(fn, context, Arguments.EMPTY, binder)
+            }
+        } catch (e: ReturnException) {
+            if (e.label == null || returnLabels.contains(e.label)) e.result
+            else throw e
+        }
+    }
+
+    fun invokeImplicitIntArgFast(scope: Scope, arg: Long): Obj? {
+        if (!supportsFastOnlyVm(Arguments.EMPTY)) return null
+        val context = buildContext(scope, Arguments.EMPTY)
+        val binder: (CmdFrame, Arguments) -> Unit = { frame, _ ->
+            slotPlanByName["it"]?.let { itSlot ->
+                frame.frame.setInt(itSlot, arg)
+            }
+        }
+        return try {
+            CmdVm().executeFastOnlyNoSuspend(fn, context, Arguments.EMPTY, binder)
         } catch (e: ReturnException) {
             if (e.label == null || returnLabels.contains(e.label)) e.result else throw e
         }
     }
+
+    suspend fun invokeWithArgs(scope: Scope, args: Arguments): Obj {
+        val context = buildContext(scope, args)
+        return try {
+            val vm = CmdVm()
+            if (supportsFastOnlyVm(args)) {
+                val binder: (CmdFrame, Arguments) -> Unit = { frame, arguments ->
+                    bindArgumentsFast(frame, context, arguments)
+                }
+                vm.executeFastOnly(fn, context, args, binder)
+            } else {
+                val binder: suspend (CmdFrame, Arguments) -> Unit = { frame, arguments ->
+                    bindArguments(frame, context, arguments)
+                    seedUndeclaredLocals(frame, context)
+                }
+                vm.execute(fn, context, args, binder)
+            }
+        } catch (e: ReturnException) {
+            if (e.label == null || returnLabels.contains(e.label)) e.result else throw e
+        }
+    }
+
+    fun invokeWithArgsFast(scope: Scope, args: Arguments): Obj? {
+        if (!supportsFastOnlyVm(args)) return null
+        val context = buildContext(scope, args)
+        val binder: (CmdFrame, Arguments) -> Unit = { frame, arguments ->
+            bindArgumentsFast(frame, context, arguments)
+        }
+        return try {
+            CmdVm().executeFastOnlyNoSuspend(fn, context, args, binder)
+        } catch (e: ReturnException) {
+            if (e.label == null || returnLabels.contains(e.label)) e.result else throw e
+        }
+    }
+
+    override fun callWithArgsFast(scope: Scope, args: Arguments): Obj? = invokeWithArgsFast(scope, args)
+
+    override fun callOnFast(scope: Scope): Obj? = invokeWithArgsFast(scope, scope.args)
+
+    override suspend fun execute(scope: Scope): Obj {
+        return invokeWithArgs(scope, scope.args)
+    }
 }
 
 class CmdIterPush(internal val iterSlot: Int) : Cmd() {
@@ -4492,6 +4739,19 @@ class CmdFrame(
         return ExecutionError(errorObject, pos, message, t)
     }
 
+    fun normalizeThrowableFast(t: Throwable): Throwable {
+        if (t is ExecutionError || t is ReturnException || t is LoopBreakContinueException) return t
+        val parentScope = ensureScope()
+        val pos = (t as? ScriptError)?.pos ?: currentErrorPos() ?: parentScope.pos
+        val throwScope = parentScope.createChildScope(pos = pos)
+        val message = when (t) {
+            is ScriptError -> t.errorMessage
+            else -> t.message ?: t.toString()
+        }
+        val errorObject = ObjUnknownException(throwScope, message)
+        return ExecutionError(errorObject, pos, message, t)
+    }
+
     suspend fun handleException(t: Throwable): Boolean {
         val handler = tryStack.lastOrNull() ?: return false
         vmIterDebug {
@@ -5446,6 +5706,14 @@ class CmdFrame(
             if (index < target.slotCount) return index
             return index
         }
+        if (target.hasSlotPlanConflict(mapOf(name to index))) {
+            val record = target.getLocalRecordDirect(name)
+                ?: target.localBindings[name]
+                ?: target.parent?.get(name)
+                ?: target.get(name)
+                ?: ObjRecord(ObjUnset, isMutable = true)
+            return target.allocateSlotFor(name, record)
+        }
         target.applySlotPlan(mapOf(name to index))
         val existing = target.getLocalRecordDirect(name) ?: target.localBindings[name]
         if (existing != null) {

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/Opcode.kt

@@ -190,6 +190,8 @@ enum class Opcode(val code: Int) {
     GET_DYNAMIC_MEMBER(0xAC),
     SET_DYNAMIC_MEMBER(0xAD),
     CALL_DYNAMIC_MEMBER(0xAE),
+    LIST_NEW_INT_CAP(0xAF),
+    LIST_FILL_INT_CAP(0xB0),
 
     RESOLVE_SCOPE_SLOT(0xB1),
     LOAD_OBJ_ADDR(0xB2),

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/SeedLocals.kt

@@ -17,7 +17,58 @@
 package net.sergeych.lyng.bytecode
 
 import net.sergeych.lyng.Scope
+import net.sergeych.lyng.FrameSlotRef
+import net.sergeych.lyng.RecordSlotRef
+import net.sergeych.lyng.ScopeSlotRef
 import net.sergeych.lyng.obj.ObjRecord
+import net.sergeych.lyng.obj.ObjProperty
+
+internal fun canFastSeedUndeclaredLocals(
+    fn: CmdFunction,
+    declaredLocalNames: Set<String>,
+    preboundLocalNames: Set<String>
+): Boolean {
+    if (fn.localSlotNames.isEmpty()) return true
+    for (i in fn.localSlotNames.indices) {
+        val name = fn.localSlotNames[i] ?: continue
+        if (declaredLocalNames.contains(name)) continue
+        if (fn.localSlotCaptures.getOrNull(i) == true) continue
+        if (preboundLocalNames.contains(name)) continue
+        return false
+    }
+    return true
+}
+
+internal fun trySeedFrameLocalsFromScopeFast(frame: CmdFrame, scope: Scope): Boolean {
+    val localNames = frame.fn.localSlotNames
+    if (localNames.isEmpty()) return true
+    val base = frame.fn.scopeSlotCount
+    for (i in localNames.indices) {
+        val name = localNames[i] ?: continue
+        val slotType = frame.getLocalSlotTypeCode(i)
+        if (slotType != SlotType.UNKNOWN.code && slotType != SlotType.OBJ.code) continue
+        if (slotType == SlotType.OBJ.code && frame.frame.getRawObj(i) != null) continue
+        val record = scope.getLocalRecordDirect(name)
+            ?: scope.chainLookupIgnoreClosure(name, followClosure = true)
+            ?: continue
+        val value = when {
+            record.type == ObjRecord.Type.Delegated -> return false
+            record.type == ObjRecord.Type.Property -> return false
+            record.value is ObjProperty -> return false
+            else -> when (val direct = record.value) {
+                is FrameSlotRef -> direct.resolvedCaptureValueOrNull() ?: return false
+                is RecordSlotRef -> direct.resolvedCaptureValueOrNull() ?: return false
+                is ScopeSlotRef -> direct.resolvedCaptureValueOrNull() ?: return false
+                else -> direct
+            }
+        }
+        if (value is FrameSlotRef && value.refersTo(frame.frame, i)) {
+            continue
+        }
+        frame.setObjUnchecked(base + i, value)
+    }
+    return true
+}
 
 internal suspend fun seedFrameLocalsFromScope(frame: CmdFrame, scope: Scope) {
     val localNames = frame.fn.localSlotNames

lynglib/src/commonMain/kotlin/net/sergeych/lyng/miniast/DocRegistrationHelpers.kt

@@ -99,10 +99,11 @@ fun ObjClass.addFnDoc(
     visibility: Visibility = Visibility.Public,
     tags: Map<String, List<String>> = emptyMap(),
     moduleName: String? = null,
+    callSignature: net.sergeych.lyng.CallSignature? = null,
     code: suspend ScopeFacade.() -> Obj
 ) {
     // Register runtime method
-    addFn(name, isOpen, visibility, code = code)
+    addFn(name, isOpen, visibility, callSignature = callSignature, code = code)
     // Register docs for the member under this class
     BuiltinDocRegistry.module(moduleName ?: ownerModuleNameFromClassOrUnknown()) {
         classDoc(this@addFnDoc.className, doc = "") {
@@ -137,9 +138,10 @@ fun ObjClass.addClassFnDoc(
     isOpen: Boolean = false,
     tags: Map<String, List<String>> = emptyMap(),
     moduleName: String? = null,
+    callSignature: net.sergeych.lyng.CallSignature? = null,
     code: suspend ScopeFacade.() -> Obj
 ) {
-    addClassFn(name, isOpen, code)
+    addClassFn(name, isOpen, callSignature, code)
     BuiltinDocRegistry.module(moduleName ?: ownerModuleNameFromClassOrUnknown()) {
         classDoc(this@addClassFnDoc.className, doc = "") {
             method(name = name, doc = doc, params = params, returns = returns, isStatic = true, tags = tags)

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

@@ -31,6 +31,7 @@ class LambdaFnRef(
     val captureEntries: List<LambdaCaptureEntry>,
     val inferredReturnClass: ObjClass?,
     val inlineBodyRef: ObjRef?,
+    val supportsDirectInvokeFastPath: Boolean,
     val preferredThisType: String?,
     val wrapAsExtensionCallable: Boolean,
     val returnLabels: Set<String>,

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

@@ -24,6 +24,7 @@ import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.JsonNull
 import kotlinx.serialization.serializer
+import net.sergeych.lyng.BytecodeCallable
 import net.sergeych.lyng.*
 import net.sergeych.lyng.InteropOperator
 import net.sergeych.lyng.OperatorInteropRegistry
@@ -723,40 +724,39 @@ open class Obj {
         scope.raiseNotImplemented()
     }
 
-    suspend fun invoke(scope: Scope, thisObj: Obj, args: Arguments, declaringClass: ObjClass? = null): Obj {
+    private suspend fun invokeWithBoundScope(
-        val usePool = PerfFlags.SCOPE_POOL && this !is Statement
+        scope: Scope,
+        args: Arguments,
+        thisObj: Obj,
+        declaringClass: ObjClass? = null,
+        atPos: Pos = scope.pos
+    ): Obj {
+        val usePool = PerfFlags.SCOPE_POOL && this !is Statement && atPos == scope.pos
         return if (usePool) {
             scope.withChildFrame(args, newThisObj = thisObj) { child ->
                 if (declaringClass != null) child.currentClassCtx = declaringClass
-                callOn(child)
+                (this as? BytecodeCallable)?.callOnFast(child) ?: callOn(child)
             }
         } else {
-            callOn(scope.createChildScope(scope.pos, args = args, newThisObj = thisObj).also {
+            val child = scope.createChildScope(atPos, args = args, newThisObj = thisObj).also {
                 if (declaringClass != null) it.currentClassCtx = declaringClass
-            })
             }
+            (this as? BytecodeCallable)?.callOnFast(child) ?: callOn(child)
+        }
+    }
+
+    suspend fun invoke(scope: Scope, thisObj: Obj, args: Arguments, declaringClass: ObjClass? = null): Obj {
+        return invokeWithBoundScope(scope, args, thisObj, declaringClass)
     }
 
     suspend fun invoke(scope: Scope, thisObj: Obj, vararg args: Obj): Obj =
-        callOn(
+        invokeWithBoundScope(scope, Arguments(args.toList()), thisObj)
-            scope.createChildScope(
-                scope.pos,
-                args = Arguments(args.toList()),
-                newThisObj = thisObj
-            )
-        )
 
     suspend fun invoke(scope: Scope, thisObj: Obj): Obj =
-        callOn(
+        invokeWithBoundScope(scope, Arguments.EMPTY, thisObj)
-            scope.createChildScope(
-                scope.pos,
-                args = Arguments.EMPTY,
-                newThisObj = thisObj
-            )
-        )
 
     suspend fun invoke(scope: Scope, atPos: Pos, thisObj: Obj, args: Arguments): Obj =
-        callOn(scope.createChildScope(atPos, args = args, newThisObj = thisObj))
+        invokeWithBoundScope(scope, args, thisObj, atPos = atPos)
 
 
     val asReadonly: ObjRecord by lazy { ObjRecord(this, false) }
@@ -828,7 +828,13 @@ open class Obj {
                 name = "let",
                 doc = "Calls the specified function block with `this` value as its argument and returns its result.",
                 params = listOf(ParamDoc("block")),
-                moduleName = "lyng.stdlib"
+                moduleName = "lyng.stdlib",
+                callSignature = CallSignature(
+                    inlineHigherOrder = CallSignature.HigherOrderInline(
+                        kind = CallSignature.Kind.UNARY_ARGUMENT,
+                        result = CallSignature.ResultMode.BLOCK_RESULT
+                    )
+                )
             ) {
                 call(args.firstAndOnly(), Arguments(thisObj))
             }
@@ -836,7 +842,13 @@ open class Obj {
                 name = "apply",
                 doc = "Calls the specified function block with `this` value as its receiver and returns `this` value.",
                 params = listOf(ParamDoc("block")),
-                moduleName = "lyng.stdlib"
+                moduleName = "lyng.stdlib",
+                callSignature = CallSignature(
+                    inlineHigherOrder = CallSignature.HigherOrderInline(
+                        kind = CallSignature.Kind.RECEIVER,
+                        result = CallSignature.ResultMode.RETURN_RECEIVER
+                    )
+                )
             ) {
                 val body = args.firstAndOnly()
                 val scope = requireScope()
@@ -852,7 +864,13 @@ open class Obj {
                 name = "also",
                 doc = "Calls the specified function block with `this` value as its argument and returns `this` value.",
                 params = listOf(ParamDoc("block")),
-                moduleName = "lyng.stdlib"
+                moduleName = "lyng.stdlib",
+                callSignature = CallSignature(
+                    inlineHigherOrder = CallSignature.HigherOrderInline(
+                        kind = CallSignature.Kind.UNARY_ARGUMENT,
+                        result = CallSignature.ResultMode.RETURN_RECEIVER
+                    )
+                )
             ) {
                 call(args.firstAndOnly(), Arguments(thisObj))
                 thisObj
@@ -861,7 +879,13 @@ open class Obj {
                 name = "run",
                 doc = "Calls the specified function block with `this` value as its receiver and returns its result.",
                 params = listOf(ParamDoc("block")),
-                moduleName = "lyng.stdlib"
+                moduleName = "lyng.stdlib",
+                callSignature = CallSignature(
+                    inlineHigherOrder = CallSignature.HigherOrderInline(
+                        kind = CallSignature.Kind.RECEIVER,
+                        result = CallSignature.ResultMode.BLOCK_RESULT
+                    )
+                )
             ) {
                 call(args.firstAndOnly())
             }

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

@@ -809,7 +809,8 @@ open class ObjClass(
                     if (initStmt is net.sergeych.lyng.Statement) {
                         executeBytecodeWithSeed(instance.instanceScope, initStmt, "instance init")
                     } else {
-                        initStmt.callOn(instance.instanceScope)
+                        (initStmt as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(instance.instanceScope)
+                            ?: initStmt.callOn(instance.instanceScope)
                     }
                 }
             } finally {
@@ -821,13 +822,14 @@ open class ObjClass(
             c.instanceConstructor?.let { ctor ->
                 val execScope =
                     instance.instanceScope.createChildScope(args = argsForThis ?: Arguments.EMPTY, newThisObj = instance)
-                ctor.callOn(execScope)
+                (ctor as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(execScope) ?: ctor.callOn(execScope)
             }
         }
     }
 
     suspend fun callWithArgs(scope: Scope, vararg plainArgs: Obj): Obj {
-        return callOn(scope.createChildScope(Arguments(*plainArgs)))
+        val child = scope.createChildScope(Arguments(*plainArgs))
+        return (this as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(child) ?: callOn(child)
     }
 
 
@@ -847,6 +849,7 @@ open class ObjClass(
         fieldId: Int? = null,
         methodId: Int? = null,
         typeDecl: net.sergeych.lyng.TypeDecl? = null,
+        callSignature: net.sergeych.lyng.CallSignature? = null,
     ): ObjRecord {
         // Validation of override rules: only for non-system declarations
         var existing: ObjRecord? = null
@@ -947,6 +950,7 @@ open class ObjClass(
             isOverride = isOverride,
             isTransient = isTransient,
             type = type,
+            callSignature = callSignature,
             typeDecl = typeDecl,
             memberName = name,
             fieldId = effectiveFieldId,
@@ -973,7 +977,8 @@ open class ObjClass(
         isTransient: Boolean = false,
         type: ObjRecord.Type = ObjRecord.Type.Field,
         fieldId: Int? = null,
-        methodId: Int? = null
+        methodId: Int? = null,
+        callSignature: net.sergeych.lyng.CallSignature? = null
     ): ObjRecord {
         initClassScope()
         val existing = classScope!!.objects[name]
@@ -1014,6 +1019,7 @@ open class ObjClass(
             writeVisibility,
             recordType = type,
             isTransient = isTransient,
+            callSignature = callSignature,
             fieldId = effectiveFieldId,
             methodId = effectiveMethodId
         )
@@ -1033,6 +1039,7 @@ open class ObjClass(
         isOverride: Boolean = false,
         pos: Pos = Pos.builtIn,
         methodId: Int? = null,
+        callSignature: net.sergeych.lyng.CallSignature? = null,
         code: (suspend net.sergeych.lyng.ScopeFacade.() -> Obj)? = null
     ) {
         val stmt = code?.let { ObjExternCallable.fromBridge { it() } } ?: ObjNull
@@ -1040,7 +1047,8 @@ open class ObjClass(
             name, stmt, isMutable, visibility, writeVisibility, pos, declaringClass,
             isAbstract = isAbstract, isClosed = isClosed, isOverride = isOverride,
             type = ObjRecord.Type.Fun,
-            methodId = methodId
+            methodId = methodId,
+            callSignature = callSignature
         )
     }
 
@@ -1072,8 +1080,19 @@ open class ObjClass(
     }
 
     fun addClassConst(name: String, value: Obj) = createClassField(name, value)
-    fun addClassFn(name: String, isOpen: Boolean = false, code: suspend net.sergeych.lyng.ScopeFacade.() -> Obj) {
+    fun addClassFn(
-        createClassField(name, ObjExternCallable.fromBridge { code() }, isOpen, type = ObjRecord.Type.Fun)
+        name: String,
+        isOpen: Boolean = false,
+        callSignature: net.sergeych.lyng.CallSignature? = null,
+        code: suspend net.sergeych.lyng.ScopeFacade.() -> Obj
+    ) {
+        createClassField(
+            name,
+            ObjExternCallable.fromBridge { code() },
+            isOpen,
+            type = ObjRecord.Type.Fun,
+            callSignature = callSignature
+        )
     }
 
 

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

@@ -142,7 +142,7 @@ object ObjDecimalSupport {
             }
             val child = requireScope().createChildScope()
             child.addConst(decimalContextVar, context)
-            block.callOn(child)
+            (block as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(child) ?: block.callOn(child)
         }
         registerBuiltinConversions(decimalClass)
         registerInterop(decimalClass)

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

@@ -64,13 +64,19 @@ open class ObjDynamic(var readCallback: Obj? = null, var writeCallback: Obj? = n
         return (callback as? BytecodeLambdaCallable)?.rebindClosure(context) ?: callback
     }
 
+    private suspend fun callCallback(callback: Obj, child: Scope): Obj {
+        return (callback as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(child) ?: callback.callOn(child)
+    }
+
     /**
      * Use read callback to dynamically resolve the field name. Note that it does not work
      * with method invocation which is implemented separately in [invokeInstanceMethod] below.
      */
     override suspend fun readField(scope: Scope, name: String): ObjRecord {
         val execBase = builderScope?.let { scope.applyClosure(it) } ?: scope
-        return readCallback?.callOn(execBase.createChildScope(Arguments(ObjString(name))))?.let {
+        return readCallback?.let { callback ->
+            callCallback(callback, execBase.createChildScope(Arguments(ObjString(name))))
+        }?.let {
             if (writeCallback != null)
                 it.asMutable
             else
@@ -90,26 +96,34 @@ open class ObjDynamic(var readCallback: Obj? = null, var writeCallback: Obj? = n
         onNotFoundResult: (suspend () -> Obj?)?
     ): Obj {
         val execBase = builderScope?.let { scope.applyClosure(it) } ?: scope
-        val over = readCallback?.callOn(execBase.createChildScope(Arguments(ObjString(name))))
+        val over = readCallback?.let { callback ->
+            callCallback(callback, execBase.createChildScope(Arguments(ObjString(name))))
+        }
         return over?.invoke(scope, scope.thisObj, args)
             ?: super.invokeInstanceMethod(scope, name, args, onNotFoundResult)
     }
 
     override suspend fun writeField(scope: Scope, name: String, newValue: Obj) {
         val execBase = builderScope?.let { scope.applyClosure(it) } ?: scope
-        writeCallback?.callOn(execBase.createChildScope(Arguments(ObjString(name), newValue)))
+        writeCallback?.let { callback ->
+            callCallback(callback, execBase.createChildScope(Arguments(ObjString(name), newValue)))
+        }
             ?: super.writeField(scope, name, newValue)
     }
 
     override suspend fun getAt(scope: Scope, index: Obj): Obj {
         val execBase = builderScope?.let { scope.applyClosure(it) } ?: scope
-        return readCallback?.callOn(execBase.createChildScope(Arguments(index)))
+        return readCallback?.let { callback ->
+            callCallback(callback, execBase.createChildScope(Arguments(index)))
+        }
             ?: super.getAt(scope, index)
     }
 
     override suspend fun putAt(scope: Scope, index: Obj, newValue: Obj) {
         val execBase = builderScope?.let { scope.applyClosure(it) } ?: scope
-        writeCallback?.callOn(execBase.createChildScope(Arguments(index, newValue)))
+        writeCallback?.let { callback ->
+            callCallback(callback, execBase.createChildScope(Arguments(index, newValue)))
+        }
             ?: super.putAt(scope, index, newValue)
     }
 
@@ -124,7 +138,7 @@ open class ObjDynamic(var readCallback: Obj? = null, var writeCallback: Obj? = n
             // Snapshot the caller scope to capture locals/args even if the runtime pools/reuses frames.
             // Module scope should stay late-bound to allow extern class rebinding and similar updates.
             delegate.builderScope = if (scope is net.sergeych.lyng.ModuleScope) null else scope.snapshotForClosure()
-            builder.callOn(buildScope)
+            (builder as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(buildScope) ?: builder.callOn(buildScope)
             return delegate
         }
 

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

@@ -395,8 +395,17 @@ suspend fun Obj.getLyngExceptionMessageWithStackTrace(scope: Scope? = null,showD
     var at = "unknown"
     val stack = if (!trace.list.isEmpty()) {
         val first = trace.list[0]
-        at = (first.readField(s, "at").value as ObjString).value
+        suspend fun formatTraceEntry(entry: Obj): String {
-        "\n" + trace.list.map { "    at " + it.toString(s).value }.joinToString("\n")
+            return when (entry) {
+                is ObjString -> entry.value.removePrefix("#")
+                else -> entry.toString(s).value
+            }
+        }
+        at = when (first) {
+            is ObjString -> formatTraceEntry(first)
+            else -> (first.readField(s, "at").value as ObjString).value
+        }
+        "\n" + trace.list.map { "    at " + formatTraceEntry(it) }.joinToString("\n")
     } else {
         val pos = s.pos
         if (pos.source.fileName.isNotEmpty() && pos.currentLine.isNotEmpty()) {

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

@@ -81,7 +81,7 @@ private suspend fun createLyngFlowInput(scope: Scope, producer: Obj, ownerSessio
     val runProducer: suspend CoroutineScope.() -> Unit = {
         var failure: Throwable? = null
         try {
-            producer.callOn(builderScope)
+            (producer as? net.sergeych.lyng.BytecodeCallable)?.callOnFast(builderScope) ?: producer.callOn(builderScope)
         } catch (x: ScriptFlowIsNoMoreCollected) {
             // premature flow closing, OK
         } catch (x: Throwable) {

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

@@ -18,6 +18,7 @@
 package net.sergeych.lyng.obj
 
 import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.CallSignature
 import net.sergeych.lyng.miniast.ParamDoc
 import net.sergeych.lyng.miniast.addFnDoc
 import net.sergeych.lyng.miniast.addPropertyDoc
@@ -189,7 +190,13 @@ val ObjIterable by lazy {
             doc = "Build a map from elements using the lambda result as key.",
             params = listOf(ParamDoc("keySelector")),
             returns = type("lyng.Map"),
-            moduleName = "lyng.stdlib"
+            moduleName = "lyng.stdlib",
+            callSignature = CallSignature(
+                inlineHigherOrder = CallSignature.HigherOrderInline(
+                    kind = CallSignature.Kind.ITERABLE,
+                    result = CallSignature.ResultMode.ASSOCIATE_BY
+                )
+            )
         ) {
             val association = requireOnlyArg<Obj>()
             val result = ObjMap()
@@ -204,7 +211,13 @@ val ObjIterable by lazy {
             doc = "Apply the lambda to each element in iteration order.",
             params = listOf(ParamDoc("action")),
             isOpen = true,
-            moduleName = "lyng.stdlib"
+            moduleName = "lyng.stdlib",
+            callSignature = CallSignature(
+                inlineHigherOrder = CallSignature.HigherOrderInline(
+                    kind = CallSignature.Kind.ITERABLE,
+                    result = CallSignature.ResultMode.FOR_EACH
+                )
+            )
         ) {
             val scope = requireScope()
             val it = thisObj.invokeInstanceMethod(scope, "iterator")
@@ -222,7 +235,13 @@ val ObjIterable by lazy {
             params = listOf(ParamDoc("transform")),
             returns = type("lyng.List"),
             isOpen = true,
-            moduleName = "lyng.stdlib"
+            moduleName = "lyng.stdlib",
+            callSignature = CallSignature(
+                inlineHigherOrder = CallSignature.HigherOrderInline(
+                    kind = CallSignature.Kind.ITERABLE,
+                    result = CallSignature.ResultMode.MAP
+                )
+            )
         ) {
             val fn = requiredArg<Obj>(0)
             val result = mutableListOf<Obj>()
@@ -238,7 +257,13 @@ val ObjIterable by lazy {
             params = listOf(ParamDoc("transform")),
             returns = type("lyng.List"),
             isOpen = true,
-            moduleName = "lyng.stdlib"
+            moduleName = "lyng.stdlib",
+            callSignature = CallSignature(
+                inlineHigherOrder = CallSignature.HigherOrderInline(
+                    kind = CallSignature.Kind.ITERABLE,
+                    result = CallSignature.ResultMode.MAP_NOT_NULL
+                )
+            )
         ) {
             val fn = requiredArg<Obj>(0)
             val result = mutableListOf<Obj>()

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

@@ -165,9 +165,9 @@ open class ObjList(initialList: MutableList<Obj> = mutableListOf()) : Obj() {
         }
     }
 
-    internal constructor(intValues: LongArray) : this(mutableListOf()) {
+    internal constructor(intValues: LongArray, size: Int = intValues.size) : this(mutableListOf()) {
         primitiveIntList = intValues
-        primitiveIntSize = intValues.size
+        primitiveIntSize = size
         boxedList = null
     }
 
@@ -519,8 +519,8 @@ open class ObjList(initialList: MutableList<Obj> = mutableListOf()) : Obj() {
                 doc = "Append one or more elements to the end of this list.",
                 moduleName = "lyng.stdlib"
             ) {
-                val l = thisAs<ObjList>().list
+                val l = thisAs<ObjList>()
-                for (a in args) l.add(a)
+                for (a in args) l.appendFast(a)
                 ObjVoid
             }
             addFnDoc(

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

@@ -19,6 +19,7 @@ package net.sergeych.lyng.obj
 
 import kotlinx.serialization.json.JsonElement
 import kotlinx.serialization.json.JsonObject
+import net.sergeych.lyng.CallSignature
 import net.sergeych.lyng.Scope
 import net.sergeych.lyng.miniast.*
 import net.sergeych.lynon.LynonDecoder
@@ -262,7 +263,15 @@ class ObjMap(val map: MutableMap<Obj, Obj> = mutableMapOf()) : Obj() {
                 doc = "Get value by key or compute, store, and return the default from a lambda.",
                 params = listOf(ParamDoc("key"), ParamDoc("default")),
                 returns = type("lyng.Any"),
-                moduleName = "lyng.stdlib"
+                moduleName = "lyng.stdlib",
+                callSignature = CallSignature(
+                    inlineHigherOrder = CallSignature.HigherOrderInline(
+                        kind = CallSignature.Kind.MAP_GET_OR_PUT,
+                        result = CallSignature.ResultMode.BLOCK_RESULT,
+                        argCount = 2,
+                        lambdaArgIndex = 1
+                    )
+                )
             ) {
                 val key = requiredArg<Obj>(0)
                 thisAs<ObjMap>().map.getOrPut(key) {

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

@@ -18,6 +18,7 @@
 package net.sergeych.lyng.obj
 
 import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.BytecodeCallable
 import net.sergeych.lyng.BytecodeBodyProvider
 import net.sergeych.lyng.Scope
 import net.sergeych.lyng.Statement
@@ -41,14 +42,16 @@ class ObjProperty(
         val instanceScope = (instance as? ObjInstance)?.instanceScope ?: instance.autoInstanceScope(scope)
         val execScope = scope.applyClosure(instanceScope).createChildScope(newThisObj = instance)
         execScope.currentClassCtx = declaringClass
+        (g as? BytecodeCallable)?.callOnFast(execScope)?.let { return it }
         return when (g) {
             is BytecodeStatement -> executeBytecodeWithSeed(execScope, g, "property getter")
             is BytecodeBodyProvider -> {
                 val body = g.bytecodeBody()
-                if (body != null) executeBytecodeWithSeed(execScope, body, "property getter") else g.callOn(execScope)
+                if (body != null) executeBytecodeWithSeed(execScope, body, "property getter")
+                else (g as? BytecodeCallable)?.callOnFast(execScope) ?: g.callOn(execScope)
             }
-            is Statement -> g.callOn(execScope)
+            is Statement -> (g as? BytecodeCallable)?.callOnFast(execScope) ?: g.callOn(execScope)
-            else -> g.callOn(execScope)
+            else -> (g as? BytecodeCallable)?.callOnFast(execScope) ?: g.callOn(execScope)
         }
     }
 
@@ -59,14 +62,16 @@ class ObjProperty(
         val instanceScope = (instance as? ObjInstance)?.instanceScope ?: instance.autoInstanceScope(scope)
         val execScope = scope.applyClosure(instanceScope).createChildScope(args = Arguments(value), newThisObj = instance)
         execScope.currentClassCtx = declaringClass
+        (s as? BytecodeCallable)?.callOnFast(execScope)?.let { return }
         when (s) {
             is BytecodeStatement -> executeBytecodeWithSeed(execScope, s, "property setter")
             is BytecodeBodyProvider -> {
                 val body = s.bytecodeBody()
-                if (body != null) executeBytecodeWithSeed(execScope, body, "property setter") else s.callOn(execScope)
+                if (body != null) executeBytecodeWithSeed(execScope, body, "property setter")
+                else (s as? BytecodeCallable)?.callOnFast(execScope) ?: s.callOn(execScope)
             }
-            is Statement -> s.callOn(execScope)
+            is Statement -> (s as? BytecodeCallable)?.callOnFast(execScope) ?: s.callOn(execScope)
-            else -> s.callOn(execScope)
+            else -> (s as? BytecodeCallable)?.callOnFast(execScope) ?: s.callOn(execScope)
         }
     }
 

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

@@ -38,17 +38,26 @@ class ImportManager(
 
     val packageNames: List<String> get() = imports.keys.toList()
 
+    private class CacheCell(var scope: ModuleScope? = null)
+
     private inner class Entry(
         val packageName: String,
         val builder: suspend (ModuleScope) -> Unit,
-        var cachedScope: ModuleScope? = null
+        val cacheCell: CacheCell = CacheCell()
     ) {
 
         suspend fun getScope(pos: Pos): ModuleScope {
-            cachedScope?.let { return it }
+            cacheCell.scope?.let { return it }
-            return ModuleScope(inner, pos, packageName).apply {
+            val module = ModuleScope(inner, pos, packageName)
-                cachedScope = this
+            cacheCell.scope = module
-                builder(this)
+            return try {
+                builder(module)
+                module
+            } catch (e: Throwable) {
+                if (cacheCell.scope === module) {
+                    cacheCell.scope = null
+                }
+                throw e
             }
         }
     }
@@ -152,14 +161,14 @@ class ImportManager(
         op.withLock {
             ImportManager(rootScope, securityManager).apply {
                 for ((name, entry) in this@ImportManager.imports) {
-                    imports[name] = Entry(entry.packageName, entry.builder, entry.cachedScope)
+                    imports[name] = Entry(entry.packageName, entry.builder, entry.cacheCell)
                 }
             }
         }
 
     fun invalidatePackageCache(name: String) {
         op.withLock {
-            imports[name]?.cachedScope = null
+            imports[name]?.cacheCell?.scope = null
         }
     }
 

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

@@ -58,7 +58,10 @@ abstract class Statement(
         val type = ObjClass("Callable")
     }
 
-    suspend fun call(scope: Scope, vararg args: Obj) = execute(scope.createChildScope(args =  Arguments(*args)))
+    suspend fun call(scope: Scope, vararg args: Obj): Obj {
+        val child = scope.createChildScope(args = Arguments(*args))
+        return (this as? BytecodeCallable)?.callOnFast(child) ?: execute(child)
+    }
 
     protected fun bytecodeOnly(scope: Scope, label: String): Nothing {
         return scope.raiseIllegalState("bytecode-only execution is required; $label needs compiled bytecode")

lynglib/src/commonTest/kotlin/BytecodeRecentOpsTest.kt

@@ -213,6 +213,24 @@ class BytecodeRecentOpsTest {
         assertEquals(4, scope.eval("calc()").toInt())
     }
 
+    @Test
+    fun listFillWithCapacityUsesPrimitiveCapacityBytecode() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                val xs = List.fill(5, 12) { it * 2 }
+                xs.add(99)
+                xs[0] + xs[4] + xs[5]
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("LIST_NEW_INT_CAP"), disasm)
+        assertFalse(disasm.contains("LIST_FILL_INT_CAP"), disasm)
+        assertEquals(107, scope.eval("calc()").toInt())
+    }
+
     @Test
     fun directLambdaLiteralCallUsesInlineBytecode() = runTest {
         val scope = Script.newScope()
@@ -229,6 +247,21 @@ class BytecodeRecentOpsTest {
         assertEquals(11, scope.eval("calc()").toInt())
     }
 
+    @Test
+    fun capturedLambdaCanCallListFillOnCapturedClassReceiver() = runTest {
+        val scope = Script.newScope()
+        val result = scope.eval(
+            """
+            fun calc(n: Int) {
+                val xs = { List.fill(n) { it } }()
+                xs[4]
+            }
+            calc(5)
+            """.trimIndent()
+        )
+        assertEquals(4, result.toInt())
+    }
+
     @Test
     fun directLambdaLiteralCallWithCaptureUsesInlineBytecode() = runTest {
         val scope = Script.newScope()
@@ -346,6 +379,106 @@ class BytecodeRecentOpsTest {
         assertEquals(12, scope.eval("calc()").toInt())
     }
 
+    @Test
+    fun nestedInlineLambdaParamCallAvoidsCallSlot() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                { g -> g(10) }({ x -> x + 1 })
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(11, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun optionalExactLambdaCallUsesInlineBytecode() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            type IntFn = (Int)->Int
+            fun calc() {
+                val f: IntFn? = { x -> x + 1 }
+                f?(10)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(11, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun conditionalExactLambdaCallUsesInlineBytecode() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            val base = { x -> x + 1 }
+            fun calc(flag: Bool) {
+                (if(flag) base else base)(10)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(11, scope.eval("calc(true)").toInt())
+    }
+
+    @Test
+    fun elvisExactLambdaCallUsesInlineBytecode() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            val base = { x -> x + 1 }
+            fun calc() {
+                (null ?: base)(10)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(11, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun castExactLambdaCallUsesInlineBytecode() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            type IntFn = (Int)->Int
+            val base: IntFn = { x -> x + 1 }
+            fun calc() {
+                (base as IntFn)(10)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(11, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun whenExactLambdaCallUsesInlineBytecode() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            val base = { x -> x + 1 }
+            fun calc(flag: Bool) {
+                (when(flag) {
+                    true -> base
+                    else -> base
+                })(10)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(11, scope.eval("calc(true)").toInt())
+    }
+
     @Test
     fun letLiteralUsesInlineBytecode() = runTest {
         val scope = Script.newScope()
@@ -501,6 +634,166 @@ class BytecodeRecentOpsTest {
         assertEquals(6, scope.eval("calc()").toInt())
     }
 
+    @Test
+    fun mapLiteralUsesDirectConstructorCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                val m = { a: 1, b: 2 }
+                m.size
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(2, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun mapEntryLiteralUsesDirectConstructorCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                val e = "a" => 2
+                e.value
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(2, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun constructorNameUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                Map().size
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(0, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun constructorAliasUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                val ctor = Map
+                val m = ctor() as Map
+                m.size
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(0, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun ifExpressionConstructorAliasUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc(flag: Bool) {
+                val ctor = if(flag) Map else Map
+                val m = ctor() as Map
+                m.size
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(0, scope.eval("calc(true)").toInt())
+    }
+
+    @Test
+    fun elvisConstructorAliasUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                val ctor = null ?: Map
+                val m = ctor() as Map
+                m.size
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(0, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun whenConstructorAliasUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc(flag: Bool) {
+                val ctor = when(flag) {
+                    true -> Map
+                    else -> Map
+                }
+                val m = ctor() as Map
+                m.size
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(0, scope.eval("calc(true)").toInt())
+    }
+
+    @Test
+    fun localNamedFunctionUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                fun twice(x: Int) { x * 2 }
+                twice(3)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(6, scope.eval("calc()").toInt())
+    }
+
+    @Test
+    fun localNamedFunctionAliasUsesDirectCall() = runTest {
+        val scope = Script.newScope()
+        scope.eval(
+            """
+            fun calc() {
+                fun twice(x: Int) { x * 2 }
+                val f = twice
+                f(3)
+            }
+            """.trimIndent()
+        )
+        val disasm = scope.disassembleSymbol("calc")
+        assertTrue(disasm.contains("CALL_DIRECT"), disasm)
+        assertFalse(disasm.contains("CALL_SLOT"), disasm)
+        assertEquals(6, scope.eval("calc()").toInt())
+    }
+
     @Test
     fun optionalIndexPreIncSkipsOnNullReceiver() = runTest {
         eval(

lynglib/src/commonTest/kotlin/CompilerVmReviewRegressionTest.kt

@@ -16,11 +16,17 @@
 
 import kotlinx.coroutines.test.runTest
 import net.sergeych.lyng.Compiler
+import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.Pos
 import net.sergeych.lyng.Scope
 import net.sergeych.lyng.Script
 import net.sergeych.lyng.ScriptError
 import net.sergeych.lyng.Source
+import net.sergeych.lyng.Statement
 import net.sergeych.lyng.asFacade
+import net.sergeych.lyng.obj.ObjDynamic
+import net.sergeych.lyng.obj.ObjInt
+import net.sergeych.lyng.obj.ObjList
 import net.sergeych.lyng.obj.ObjString
 import net.sergeych.lyng.obj.toInt
 import net.sergeych.lyng.pacman.ImportManager
@@ -68,6 +74,235 @@ class CompilerVmReviewRegressionTest {
         assertContains(ex.errorMessage, "module binding 'answer'")
     }
 
+    @Test
+    fun facadeCallUsesPreparedLambdaWithArgs() = runTest {
+        val lambda = Compiler.compile(
+            Source(
+                "<facade-call-lambda>",
+                """
+                val base = 2
+                { x -> x + base }
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val callable = lambda.execute(scope)
+        assertEquals(42, scope.asFacade().call(callable, Arguments(ObjInt.of(40))).toInt())
+    }
+
+    @Test
+    fun genericInvokeHelpersUsePreparedLambdaEntryPoints() = runTest {
+        val unaryLambda = Compiler.compile(
+            Source(
+                "<generic-invoke-unary>",
+                """
+                val delta = 2
+                { x -> x + delta }
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+        val nullaryLambda = Compiler.compile(
+            Source(
+                "<generic-invoke-nullary>",
+                """
+                val base = 7
+                { base }
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val unaryScope = Script.newScope()
+        val nullaryScope = Script.newScope()
+        val unaryCallable = unaryLambda.execute(unaryScope)
+        val nullaryCallable = nullaryLambda.execute(nullaryScope)
+
+        assertEquals(42, unaryCallable.invoke(unaryScope, ObjString("receiver"), ObjInt.of(40)).toInt())
+        assertEquals(7, nullaryCallable.invoke(nullaryScope, ObjString("receiver")).toInt())
+        assertEquals(
+            42,
+            unaryCallable.invoke(
+                unaryScope,
+                Pos(Source("<generic-invoke-pos>", ""), 0, 0),
+                ObjString("receiver"),
+                Arguments(ObjInt.of(40))
+            ).toInt()
+        )
+    }
+
+    @Test
+    fun statementCallUsesPreparedLambdaFastPath() = runTest {
+        val unaryLambda = Compiler.compile(
+            Source(
+                "<statement-call-unary>",
+                """
+                val delta = 2
+                { x -> x + delta }
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val callable = unaryLambda.execute(scope) as Statement
+
+        assertEquals(42, callable.call(scope, ObjInt.of(40)).toInt())
+    }
+
+    @Test
+    fun preparedLambdaKeepsImmutableModuleCaptureAcrossOtherScriptsInSameScope() = runTest {
+        val unaryLambda = Compiler.compile(
+            Source(
+                "<cross-script-capture-unary>",
+                """
+                val delta = 2
+                { x -> x + delta }
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+        val unrelatedScript = Compiler.compile(
+            Source(
+                "<cross-script-capture-unrelated>",
+                """
+                val base = 7
+                base
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val callable = unaryLambda.execute(scope) as Statement
+        unrelatedScript.execute(scope)
+
+        assertEquals(42, callable.call(scope, ObjInt.of(40)).toInt())
+        assertEquals(42, scope.asFacade().call(callable, Arguments(ObjInt.of(40))).toInt())
+    }
+
+    @Test
+    fun dynamicCallbacksUsePreparedLambdaFastPath() = runTest {
+        val script = Compiler.compile(
+            Source(
+                "<dynamic-fast-callbacks>",
+                """
+                var seen = ""
+                dynamic {
+                    get { name -> name + seen }
+                    set { name, value -> seen = name + "=" + value }
+                }
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val dynamic = script.execute(scope) as ObjDynamic
+
+        assertEquals("foo", (dynamic.readField(scope, "foo").value as ObjString).value)
+        dynamic.writeField(scope, "foo", ObjInt.of(7))
+        assertEquals("barfoo=7", (dynamic.getAt(scope, ObjString("bar")) as ObjString).value)
+    }
+
+    @Test
+    fun higherOrderMethodInliningSupportsCapturedValues() = runTest {
+        val script = Compiler.compile(
+            Source(
+                "<higher-order-inline-captures>",
+                """
+                val suffix = "!"
+                val offset = 10
+                var sum = 0
+
+                val letResult = "a".let { it + suffix }
+                val applyResult = List<Int>().apply { add(offset); add(offset + 1) }
+                val mapped = [1, 2, 3].map { it + offset }
+                val filtered = [1, 2, 3].filter { it + offset >= 12 }
+                val notNull = [1, 2, 3].mapNotNull { if (it + offset >= 12) it + offset else null }
+                val associated = [1, 2, 3].associateBy { "k" + (it + offset) }
+                [1, 2, 3].forEach { sum += it + offset }
+
+                [letResult, applyResult, mapped, filtered, notNull, associated, sum]
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val result = script.execute(scope) as ObjList
+
+        assertEquals("a!", (result.list[0] as ObjString).value)
+        val applied = result.list[1] as ObjList
+        assertEquals(listOf(10, 11), applied.list.map { it.toInt() })
+
+        val mapped = result.list[2] as ObjList
+        assertEquals(listOf(11, 12, 13), mapped.list.map { it.toInt() })
+
+        val filtered = result.list[3] as ObjList
+        assertEquals(listOf(2, 3), filtered.list.map { it.toInt() })
+
+        val notNull = result.list[4] as ObjList
+        assertEquals(listOf(12, 13), notNull.list.map { it.toInt() })
+
+        val associated = result.list[5].toString(scope).value
+        assertContains(associated, "\"k11\" => 1")
+        assertContains(associated, "\"k12\" => 2")
+        assertContains(associated, "\"k13\" => 3")
+
+        assertEquals(36, result.list[6].toInt())
+    }
+
+    @Test
+    fun directLambdaInliningMatchesImplicitItInvocationSemantics() = runTest {
+        val script = Compiler.compile(
+            Source(
+                "<direct-inline-it-semantics>",
+                """
+                val zeroFn = { if (it == void) 1 else 0 }
+                val multiFn = { it }
+                val zero = zeroFn()
+                val multi = multiFn(1, 2, 3)
+                [zero, multi]
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val result = script.execute(scope) as ObjList
+
+        assertEquals(1, result.list[0].toInt())
+        val multi = result.list[1] as ObjList
+        assertEquals(listOf(1, 2, 3), multi.list.map { it.toInt() })
+    }
+
+    @Test
+    fun mapGetOrPutUsesInlineDefaultLambda() = runTest {
+        val script = Compiler.compile(
+            Source(
+                "<map-get-or-put-inline>",
+                """
+                val offset = 10
+                val m = Map()
+                val first = m.getOrPut("k") { offset + 1 }
+                val second = m.getOrPut("k") { offset + 2 }
+                [first, second, m["k"]]
+                """.trimIndent()
+            ),
+            Script.defaultImportManager
+        )
+
+        val scope = Script.newScope()
+        val result = script.execute(scope) as ObjList
+
+        assertEquals(11, result.list[0].toInt())
+        assertEquals(11, result.list[1].toInt())
+        assertEquals(11, result.list[2].toInt())
+    }
+
     @Test
     fun subjectlessWhenReportsScriptError() = runTest {
         val ex = assertFailsWith<ScriptError> {

lynglib/src/commonTest/kotlin/net/sergeych/lyng/OptTest.kt

@@ -17,10 +17,12 @@
 
 package net.sergeych.lyng
 
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.test.runTest
 import net.sergeych.lyng.obj.toInt
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.TimeSource
 
 class OptTest {
@@ -40,9 +42,11 @@ class OptTest {
         repeat(3) { pass ->
             val size = scope.eval("buildArray(200000)").toInt()
             assertEquals(200000, size, "warmup pass ${pass + 1} failed")
+            delay(100)
         }
 
-        val passes = 3
+
+        val passes = 4
         var bestMs = Long.MAX_VALUE
         var totalMs = 0L
         repeat(passes) { pass ->
@@ -56,4 +60,25 @@ class OptTest {
         }
         println("add-to-array best=${bestMs}ms avg=${totalMs / passes}ms after warmup")
     }
+
+    @Test
+    fun testAddToArray2() = runTest {
+        eval(
+            $$"""
+                import lyng.time
+                val n = 700_000
+                fun tm<T>(block: ()->T): T {
+                    val t = Instant()
+                    block().also {
+                        println("tm: ${Instant() - t}")
+                    }
+                }
+                val x = tm { List.fill(n) { it * 10 + 1 } }
+                val y = tm { List.fill(n, n + 10) { it * 10 + 1 } }
+                tm { x.add(-1) }
+                tm { y.add(-2) }
+        """.trimIndent()
+        )
+    }
 }
+

notes/ai_state.md

@@ -13,6 +13,11 @@ Current focus
 Key recent changes
 - Updated AI helper docs to reflect static typing, type expressions, and compile-time-only name resolution.
 - Added stdlib random API: `Random` and deterministic `SeededRandom` with `nextInt`, `nextFloat`, and generic `next(range)`.
+- Generalized primitive list optimization for compiler-generated `List.fill`:
+  - `List.fill(size) { intExpr }` and `List.fill(size, capacity) { intExpr }` now both have bytecode fast paths.
+  - Added `LIST_NEW_INT_CAP` / `LIST_FILL_INT_CAP` for the 3-arg capacity-preserving form.
+- Fixed `ObjList.add(...)` to preserve primitive-int backing storage instead of forcing boxing through `.list`.
+- `OptTest.testAddToArray2` no longer shows the old 10x anomaly for `List.fill(n, n + 10)` or append-to-extended-list.
 
 Known failing tests
 - None in :lynglib:jvmTest after Random/SeededRandom integration.

notes/fast_ops_optimizations_plan.md

@@ -22,18 +22,25 @@ Candidates (not started)
 6) Box/unbox audit (done)
    - Unbox ObjInt/ObjReal in assign-op when target is INT/REAL to avoid boxing + obj ops.
    - MixedCompareBenchmarkTest: 240 ms -> 234 ms.
-7) Mixed compare coverage
+7) Primitive list fill with capacity (done)
+   - Extended the compiler/runtime fast path from `List.fill(size) { intExpr }` to `List.fill(size, capacity) { intExpr }`.
+   - Added `LIST_NEW_INT_CAP` and `LIST_FILL_INT_CAP` so the 3-arg form keeps primitive-int storage instead of falling back to generic stdlib code.
+   - `OptTest.testAddToArray2`: `List.fill(n, n + 10) { ... }` dropped from the prior anomaly (~10x slower than 2-arg fill) to the same range as `List.fill(n) { ... }`, roughly `56-67 ms` vs `46-75 ms` after warmup.
+8) Primitive list append preservation (done)
+   - Fixed `ObjList.add(...)` to append through the primitive-aware fast path instead of forcing `.list` and boxing the backing storage.
+   - `OptTest.testAddToArray2`: appending to the pre-extended list dropped from the prior anomaly (~10x slower) to sub-millisecond / low-millisecond timings (`~0.05-0.16 ms` for the extended list path, `~1.6-4.3 ms` for the baseline path, depending on warmup).
+9) Mixed compare coverage
    - Emit CMP_*_REAL when one operand is known ObjReal in more expression forms (not just assign-op).
    - Verify with disassembly that fast cmp opcodes are emitted.
-8) Range-loop invariant hoist
+10) Range-loop invariant hoist
    - Cache range end/step into temps once per loop; avoid repeated slot reads/boxing in body.
    - Confirm no extra CONST_OBJ in hot path.
-9) Boxing elision pass
+11) Boxing elision pass
    - Remove redundant BOX_OBJ when value feeds only primitive ops afterward (local liveness).
    - Ensure no impact on closures/escaping values.
-10) Closed-type fast paths expansion
+12) Closed-type fast paths expansion
    - Apply closed-type trust for ObjBool/ObjInt/ObjReal/ObjString in ternaries and conditional chains.
    - Guard with exact non-null temp/slot checks only.
-11) VM hot op micro-optimizations
+13) VM hot op micro-optimizations
    - Reduce frame reads/writes in ADD_INT, MUL_REAL, CMP_*_INT/REAL when operands are temps.
    - Compare against baseline; revert if regression after 10-run median.

notes/non_suspending_call_optimization_plan.md

@@ -0,0 +1,146 @@
+# Non-Suspending Call Optimization Plan
+
+## Current state
+
+Completed in the current phase:
+
+- Higher-order lambda inlining is now metadata-driven through `CallSignature`.
+- Built-in member methods (`let`, `also`, `apply`, `run`, `forEach`, `map`, `mapNotNull`, `associateBy`, `getOrPut`) publish inline metadata at declaration sites.
+- Lyng extension wrappers now preserve and expose `callSignature`, so extension methods such as `Iterable.filter` use the same inlining path as built-in members.
+- `BytecodeCompiler` no longer relies on a backend hardcoded name table for these higher-order inlining cases.
+- JVM tests are green after the metadata move.
+
+Primary motivation remains unchanged: suspend call overhead is still significant, and lambda inlining only removes part of it.
+
+## Constraints
+
+- Keep source positions, stack traces, and throw-site reporting correct.
+- Do not reintroduce one-off special cases tied to specific stdlib method names.
+- Prefer declaration metadata and reusable compiler/runtime mechanisms.
+- Preserve Kotlin Multiplatform compatibility in `commonMain`.
+- Avoid changing public language semantics just to optimize the runtime path.
+
+## Why this is the next step
+
+Lambda inlining helps when the callee body is directly available at the call site.
+The next large remaining cost is calling compiled functions through suspend entry points even when the generated body never suspends.
+
+That suggests a second optimization track:
+
+1. detect bytecode callables that are safe to execute through a non-suspending fast path;
+2. route direct calls to that path when the caller can prove it is safe;
+3. keep the suspend path as the fallback for correctness.
+
+## Proposed phases
+
+### Phase 1: Define "non-suspending compiled callable"
+
+Add explicit metadata on compiled functions / lambdas indicating whether their bytecode body may suspend.
+
+Requirements:
+
+- Computed once during bytecode generation.
+- Conservative: false negatives are acceptable; false positives are not.
+- Must account for:
+  - direct suspend-capable call opcodes;
+  - flow / coroutine constructs;
+  - delegated runtime helpers that may suspend;
+  - nested lambda creation if invocation may suspend.
+
+Likely implementation direction:
+
+- store `maySuspend` or `fastOnly`-adjacent metadata on `CmdFunction` or the callable wrapper;
+- derive it from emitted bytecode opcodes and embedded lambda constants.
+
+### Phase 2: Add a direct non-suspending invoke path
+
+For bytecode callables proven non-suspending, add an execution entry point that avoids suspend machinery for ordinary direct calls.
+
+Requirements:
+
+- Reuse as much of the existing fast frame setup as possible.
+- Keep exception translation and source mapping identical to the suspend path.
+- Do not depend on JVM-only tricks.
+
+Potential direction:
+
+- extend `BytecodeCallable` with a capability query or richer fast-call API;
+- let call sites choose among:
+  - inline body
+  - non-suspending compiled call
+  - existing suspend call
+
+### Phase 3: Teach bytecode call sites to use it
+
+Apply the new path only where the callee is known precisely.
+
+Initial targets:
+
+- direct lambda invocation where exact lambda ref is known but inlining is not possible;
+- direct local function calls where the binding resolves to a compiled callable;
+- extension wrapper calls where wrapper binding is known and non-suspending.
+
+Do not start with dynamic dispatch or reflective calls.
+
+### Phase 4: Validate behavioral fidelity
+
+Must explicitly verify:
+
+- thrown exceptions still report the same Lyng source positions;
+- stack traces remain useful enough for debugging;
+- optional calls / null propagation are unchanged;
+- captures and implicit `this` still bind correctly.
+
+### Phase 5: Measure before broadening
+
+Benchmark after each widening step, especially:
+
+- `OptTest.testAddToArray`
+- iterable pipeline samples using `filter` / `map`
+- direct lambda call microbenchmarks
+- closure-heavy samples with captures
+
+## Open technical questions
+
+1. Where should non-suspending capability live?
+   - `CmdFunction`
+   - `BytecodeStatement`
+   - callable wrapper object
+   - `CallSignature`-adjacent metadata
+
+2. Should the compiler emit a separate opcode for known non-suspending compiled calls, or should runtime dispatch pick the fast path from a normal call opcode?
+
+3. Can we preserve the current error/stack behavior if we bypass suspend wrappers entirely, or do we need a thin compatibility layer?
+
+4. Should capture-free and capture-heavy compiled lambdas share the same direct-call mechanism, or should captured callables stay on the safer path initially?
+
+## Suggested order of execution
+
+1. Add conservative `maySuspend` analysis for compiled bytecode functions.
+2. Expose a non-suspending direct-call capability on compiled callables.
+3. Use it for exact direct lambda calls first.
+4. Extend to exact local function calls.
+5. Re-measure.
+6. Only then consider broader dispatch sites.
+
+## Validation checklist
+
+- `./gradlew :lynglib:compileKotlinJvm --console=plain`
+- `./gradlew :lynglib:jvmTest --tests net.sergeych.lyng.OptTest.testAddToArray --console=plain`
+- `./gradlew :lynglib:jvmTest --tests StdlibTest.testIterableFilter --tests CompilerVmReviewRegressionTest --console=plain`
+- `./gradlew :lynglib:jvmTest --console=plain`
+
+## Notes from the completed phase
+
+Relevant current commits before this follow-up work:
+
+- `3be2892` Use fast compiled callbacks in dynamic and flow helpers
+- `1d5caaa` Broaden lambda method inlining with captures
+- `0c3242c` Generalize higher-order lambda inlining
+- `f4ab2eb` Extend lambda inlining to getOrPut and implicit it calls
+
+Current working tree phase adds:
+
+- metadata-driven higher-order inlining through member and extension signatures;
+- extension wrapper signature propagation;
+- removal of the compiler-side higher-order name table fallback.