diff --git a/compiler/build.gradle b/compiler/build.gradle
index 129cbb240..45f67efa4 100644
--- a/compiler/build.gradle
+++ b/compiler/build.gradle
@@ -1,5 +1,5 @@
 plugins {
-    id "org.jetbrains.kotlin.jvm" version "1.3.30"
+    id "org.jetbrains.kotlin.jvm" version "1.3.40"
     id 'application'
 }
 
@@ -8,7 +8,7 @@ repositories {
     jcenter()
 }
 
-def kotlinVersion = '1.3.30'
+def kotlinVersion = '1.3.40'
 
 dependencies {
     implementation project(':parser')
diff --git a/compiler/res/version.txt b/compiler/res/version.txt
index d3bdbdf1f..625934097 100644
--- a/compiler/res/version.txt
+++ b/compiler/res/version.txt
@@ -1 +1 @@
-1.7
+1.8
diff --git a/compiler/src/prog8/CompilerMain.kt b/compiler/src/prog8/CompilerMain.kt
index 09af5abad..8bf5a3959 100644
--- a/compiler/src/prog8/CompilerMain.kt
+++ b/compiler/src/prog8/CompilerMain.kt
@@ -8,6 +8,7 @@ import prog8.optimizing.constantFold
 import prog8.optimizing.optimizeStatements
 import prog8.optimizing.simplifyExpressions
 import prog8.parser.ParsingFailedError
+import prog8.parser.importLibraryModule
 import prog8.parser.importModule
 import java.io.File
 import java.io.PrintStream
@@ -71,60 +72,65 @@ private fun compileMain(args: Array<String>) {
 
     try {
         val totalTime = measureTimeMillis {
-            // import main module and process additional imports
+            // import main module and everything it needs
             println("Parsing...")
-            val moduleAst = importModule(filepath)
-            moduleAst.linkParents()
-            var namespace = moduleAst.definingScope()
-
-            // determine special compiler options
-
-            val compilerOptions = determineCompilationOptions(moduleAst)
+            val programAst = Program(filepath.fileName.toString(), mutableListOf())
+            importModule(programAst, filepath)
 
+            val compilerOptions = determineCompilationOptions(programAst)
             if (compilerOptions.launcher == LauncherType.BASIC && compilerOptions.output != OutputType.PRG)
-                throw ParsingFailedError("${moduleAst.position} BASIC launcher requires output type PRG.")
+                throw ParsingFailedError("${programAst.modules.first().position} BASIC launcher requires output type PRG.")
+
+            // if we're producing a PRG or BASIC program, include the c64utils and c64lib libraries
+            if(compilerOptions.launcher==LauncherType.BASIC || compilerOptions.output==OutputType.PRG) {
+                importLibraryModule(programAst, "c64lib")
+                importLibraryModule(programAst, "c64utils")
+            }
+
+            // always import prog8lib and math
+            importLibraryModule(programAst, "math")
+            importLibraryModule(programAst, "prog8lib")
+
 
             // perform initial syntax checks and constant folding
             println("Syntax check...")
-            val heap = HeapValues()
             val time1= measureTimeMillis {
-                moduleAst.checkIdentifiers(namespace)
+                programAst.checkIdentifiers()
             }
             //println(" time1: $time1")
             val time2 = measureTimeMillis {
-                moduleAst.constantFold(namespace, heap)
+                programAst.constantFold()
             }
             //println(" time2: $time2")
             val time3 = measureTimeMillis {
-                moduleAst.reorderStatements(namespace,heap)     // reorder statements to please the compiler later
+                programAst.reorderStatements()     // reorder statements to please the compiler later
             }
             //println(" time3: $time3")
             val time4 = measureTimeMillis {
-                moduleAst.checkValid(namespace, compilerOptions, heap)          // check if tree is valid
+                programAst.checkValid(compilerOptions)          // check if tree is valid
             }
             //println(" time4: $time4")
 
-            moduleAst.checkIdentifiers(namespace)
+            programAst.checkIdentifiers()
             if(optimize) {
                 // optimize the parse tree
                 println("Optimizing...")
                 while (true) {
                     // keep optimizing expressions and statements until no more steps remain
-                    val optsDone1 = moduleAst.simplifyExpressions(namespace, heap)
-                    val optsDone2 = moduleAst.optimizeStatements(namespace, heap)
+                    val optsDone1 = programAst.simplifyExpressions()
+                    val optsDone2 = programAst.optimizeStatements()
                     if (optsDone1 + optsDone2 == 0)
                         break
                 }
             }
 
-            namespace = moduleAst.definingScope()       // create it again, it could have changed in the meantime
-            moduleAst.checkValid(namespace, compilerOptions, heap)          // check if final tree is valid
-            moduleAst.checkRecursion(namespace)         // check if there are recursive subroutine calls
+            programAst.checkValid(compilerOptions)          // check if final tree is valid
+            programAst.checkRecursion()         // check if there are recursive subroutine calls
 
             // namespace.debugPrint()
 
             // compile the syntax tree into stackvmProg form, and optimize that
-            val compiler = Compiler(moduleAst, namespace, heap)
+            val compiler = Compiler(programAst)
             val intermediate = compiler.compile(compilerOptions)
             if(optimize)
                 intermediate.optimize()
@@ -140,7 +146,7 @@ private fun compileMain(args: Array<String>) {
             if(writeAssembly) {
                 val zeropage = C64Zeropage(compilerOptions)
                 intermediate.allocateZeropage(zeropage)
-                val assembly = AsmGen(compilerOptions, intermediate, heap, zeropage).compileToAssembly(optimize)
+                val assembly = AsmGen(compilerOptions, intermediate, programAst.heap, zeropage).compileToAssembly(optimize)
                 assembly.assemble(compilerOptions)
                 programname = assembly.name
             }
@@ -180,7 +186,9 @@ private fun compileMain(args: Array<String>) {
     }
 }
 
-fun determineCompilationOptions(moduleAst: Module): CompilationOptions {
+
+fun determineCompilationOptions(program: Program): CompilationOptions {
+    val moduleAst = program.modules.first()
     val options = moduleAst.statements.filter { it is Directive && it.directive == "%option" }.flatMap { (it as Directive).args }.toSet()
     val outputType = (moduleAst.statements.singleOrNull { it is Directive && it.directive == "%output" }
             as? Directive)?.args?.single()?.name?.toUpperCase()
diff --git a/compiler/src/prog8/ast/AST.kt b/compiler/src/prog8/ast/AST.kt
index 58af745ad..796b6badb 100644
--- a/compiler/src/prog8/ast/AST.kt
+++ b/compiler/src/prog8/ast/AST.kt
@@ -130,6 +130,10 @@ data class Position(val file: String, val line: Int, val startCol: Int, val endC
 
 
 interface IAstProcessor {
+    fun process(program: Program) {
+        program.modules.forEach { process(it) }
+    }
+
     fun process(module: Module) {
         module.statements = module.statements.asSequence().map { it.process(this) }.toMutableList()
     }
@@ -301,6 +305,13 @@ interface Node {
     val position: Position
     var parent: Node             // will be linked correctly later (late init)
     fun linkParents(parent: Node)
+
+    fun definingModule(): Module {
+        if(this is Module)
+            return this
+        return findParentNode<Module>(this)!!
+    }
+
     fun definingScope(): INameScope {
         val scope = findParentNode<INameScope>(this)
         if(scope!=null) {
@@ -398,22 +409,27 @@ interface INameScope {
     fun allLabelsAndVariables(): Set<String> =
             statements.filterIsInstance<Label>().map { it.name }.toSet() + statements.filterIsInstance<VarDecl>().map { it.name }.toSet()
 
-    fun lookup(scopedName: List<String>, statement: Node) : IStatement? {
+    fun lookup(scopedName: List<String>, localContext: Node) : IStatement? {
         if(scopedName.size>1) {
-            // it's a qualified name, look it up from the namespace root
-            var scope: INameScope? = this
-            scopedName.dropLast(1).forEach {
-                scope = scope?.subScopes()?.get(it)
-                if(scope==null)
-                    return null
+            // it's a qualified name, look it up from the root of the module's namespace (consider all modules in the program)
+            for(module in localContext.definingModule().program.modules) {
+                var scope: INameScope? = module
+                for(name in scopedName.dropLast(1)) {
+                    scope = scope?.subScopes()?.get(name)
+                    if(scope==null)
+                        break
+                }
+                if(scope!=null) {
+                    val result = scope.getLabelOrVariable(scopedName.last())
+                    if(result!=null)
+                        return result
+                    return scope.subScopes()[scopedName.last()] as IStatement?
+                }
             }
-            val foundScope : INameScope = scope!!
-            return foundScope.getLabelOrVariable(scopedName.last())
-                    ?:
-                    foundScope.subScopes()[scopedName.last()] as IStatement?
+            return null
         } else {
-            // unqualified name, find the scope the statement is in, look in that first
-            var statementScope = statement
+            // unqualified name, find the scope the localContext is in, look in that first
+            var statementScope = localContext
             while(statementScope !is ParentSentinel) {
                 val localScope = statementScope.definingScope()
                 val result = localScope.getLabelOrVariable(scopedName[0])
@@ -460,12 +476,26 @@ class BuiltinFunctionStatementPlaceholder(val name: String, override val positio
     override fun definingScope(): INameScope = BuiltinFunctionScopePlaceholder
 }
 
+
+
+/*********** Everything starts from here, the Program; zero or more modules *************/
+
+class Program(val name: String, val modules: MutableList<Module>) {
+    val namespace = GlobalNamespace(modules)
+    val heap = HeapValues()
+
+    val loadAddress: Int
+        get() = modules.first().loadAddress
+}
+
+
 class Module(override val name: String,
              override var statements: MutableList<IStatement>,
              override val position: Position,
              val isLibraryModule: Boolean,
-             val importedFrom: Path) : Node, INameScope {
+             val source: Path) : Node, INameScope {
     override lateinit var parent: Node
+    lateinit var program: Program
 
     override fun linkParents(parent: Node) {
         this.parent=parent
@@ -478,28 +508,31 @@ class Module(override val name: String,
         statements.forEach {it.linkParents(this)}
     }
 
-    fun process(processor: IAstProcessor) {
-        processor.process(this)
-    }
+    override fun definingScope(): INameScope = program.namespace
 
-    override fun definingScope(): INameScope = GlobalNamespace("<<<global>>>", statements, position)
+    override fun toString() = "Module(name=$name, pos=$position, lib=$isLibraryModule)"
 }
 
 
-private class GlobalNamespace(override val name: String,
-                              override var statements: MutableList<IStatement>,
-                              override val position: Position) : INameScope {
-    override var parent = ParentSentinel
-    override fun linkParents(parent: Node) {}
+class GlobalNamespace(val modules: List<Module>): INameScope {
+    override val name = "<<<global>>>"
+    override val position = Position("<<<global>>>", 0, 0, 0)
+    override val statements = mutableListOf<IStatement>()
+    override val parent: Node = ParentSentinel
 
-    override fun lookup(scopedName: List<String>, statement: Node): IStatement? {
-        if(scopedName.size==1 && scopedName[0] in BuiltinFunctions) {
-            // builtin functions always exist, return a dummy statement for them
-            val builtinPlaceholder = Label("builtin::${scopedName.last()}", statement.position)
+    override fun linkParents(parent: Node) {
+        modules.forEach { it.linkParents(ParentSentinel) }
+    }
+
+    override fun lookup(scopedName: List<String>, localContext: Node): IStatement? {
+        if (scopedName.size == 1 && scopedName[0] in BuiltinFunctions) {
+            // builtin functions always exist, return a dummy localContext for them
+            val builtinPlaceholder = Label("builtin::${scopedName.last()}", localContext.position)
             builtinPlaceholder.parent = ParentSentinel
             return builtinPlaceholder
         }
-        val stmt = super.lookup(scopedName, statement)
+
+        val stmt = localContext.definingModule().lookup(scopedName, localContext)
         return when (stmt) {
             is Label, is VarDecl, is Block, is Subroutine -> stmt
             null -> null
@@ -813,6 +846,7 @@ data class AssignTarget(val register: Register?,
 
 
 interface IExpression: Node {
+    // TODO pass programAst instead of namespace + heap?
     fun isIterable(namespace: INameScope, heap: HeapValues): Boolean
     fun constValue(namespace: INameScope, heap: HeapValues): LiteralValue?
     fun process(processor: IAstProcessor): IExpression
@@ -1816,9 +1850,9 @@ class RepeatLoop(var body: AnonymousScope,
 
 /***************** Antlr Extension methods to create AST ****************/
 
-fun prog8Parser.ModuleContext.toAst(name: String, isLibrary: Boolean, importedFrom: Path) : Module {
+fun prog8Parser.ModuleContext.toAst(name: String, isLibrary: Boolean, source: Path) : Module {
     val nameWithoutSuffix = if(name.endsWith(".p8")) name.substringBeforeLast('.') else name
-    return Module(nameWithoutSuffix, modulestatement().asSequence().map { it.toAst(isLibrary) }.toMutableList(), toPosition(), isLibrary, importedFrom)
+    return Module(nameWithoutSuffix, modulestatement().asSequence().map { it.toAst(isLibrary) }.toMutableList(), toPosition(), isLibrary, source)
 }
 
 
diff --git a/compiler/src/prog8/ast/AstChecker.kt b/compiler/src/prog8/ast/AstChecker.kt
index f778d94aa..4604fb6c0 100644
--- a/compiler/src/prog8/ast/AstChecker.kt
+++ b/compiler/src/prog8/ast/AstChecker.kt
@@ -13,9 +13,9 @@ import java.io.File
  * General checks on the Ast
  */
 
-fun Module.checkValid(globalNamespace: INameScope, compilerOptions: CompilationOptions, heap: HeapValues) {
-    val checker = AstChecker(globalNamespace, compilerOptions, heap)
-    this.process(checker)
+fun Program.checkValid(compilerOptions: CompilationOptions) {
+    val checker = AstChecker(namespace, compilerOptions, heap)
+    checker.process(this)
     printErrors(checker.result(), name)
 }
 
@@ -66,6 +66,56 @@ private class AstChecker(private val namespace: INameScope,
         return checkResult
     }
 
+    override fun process(program: Program) {
+        // there must be a single 'main' block with a 'start' subroutine for the program entry point.
+        val mainBlocks = program.modules.flatMap { it.statements }.filter { b -> b is Block && b.name=="main" }.map { it as Block }
+        if(mainBlocks.size>1)
+            checkResult.add(SyntaxError("more than one 'main' block", mainBlocks[0].position))
+
+        for(mainBlock in mainBlocks) {
+            val startSub = mainBlock.subScopes().get("start") as? Subroutine
+            if (startSub == null) {
+                checkResult.add(SyntaxError("missing program entrypoint ('start' subroutine in 'main' block)", mainBlock.position))
+            } else {
+                if (startSub.parameters.isNotEmpty() || startSub.returntypes.isNotEmpty())
+                    checkResult.add(SyntaxError("program entrypoint subroutine can't have parameters and/or return values", startSub.position))
+            }
+
+            // the main module cannot contain 'regular' statements (they will never be executed!)
+            for (statement in mainBlock.statements) {
+                val ok = when (statement) {
+                    is Block -> true
+                    is Directive -> true
+                    is Label -> true
+                    is VarDecl -> true
+                    is InlineAssembly -> true
+                    is INameScope -> true
+                    is VariableInitializationAssignment -> true
+                    else -> false
+                }
+                if (!ok) {
+                    checkResult.add(SyntaxError("main block contains regular statements, this is not allowed (they'll never get executed). Use subroutines.", statement.position))
+                    break
+                }
+            }
+        }
+
+        // there can be an optional single 'irq' block with a 'irq' subroutine in it,
+        // which will be used as the 60hz irq routine in the vm if it's present
+        val irqBlocks = program.modules.flatMap { it.statements }.filter { it is Block && it.name=="irq" }.map { it as Block }
+        if(irqBlocks.size>1)
+            checkResult.add(SyntaxError("more than one 'irq' block", irqBlocks[0].position))
+        for(irqBlock in irqBlocks) {
+            val irqSub = irqBlock?.subScopes()?.get("irq") as? Subroutine
+            if (irqSub != null) {
+                if (irqSub.parameters.isNotEmpty() || irqSub.returntypes.isNotEmpty())
+                    checkResult.add(SyntaxError("irq entrypoint subroutine can't have parameters and/or return values", irqSub.position))
+            }
+        }
+
+        super.process(program)
+    }
+
     override fun process(module: Module) {
         super.process(module)
         val directives = module.statements.filterIsInstance<Directive>().groupBy { it.directive }
@@ -75,45 +125,6 @@ private class AstChecker(private val namespace: INameScope,
                     entry.value.mapTo(checkResult) { SyntaxError("directive can just occur once", it.position) }
             }
         }
-
-        // there must be a 'main' block with a 'start' subroutine for the program entry point.
-        val mainBlock = module.statements.singleOrNull { it is Block && it.name=="main" } as? Block?
-        val startSub = mainBlock?.subScopes()?.get("start") as? Subroutine
-        if(startSub==null) {
-            checkResult.add(SyntaxError("missing program entrypoint ('start' subroutine in 'main' block)", module.position))
-        } else {
-            if(startSub.parameters.isNotEmpty() || startSub.returntypes.isNotEmpty())
-                checkResult.add(SyntaxError("program entrypoint subroutine can't have parameters and/or return values", startSub.position))
-        }
-
-        if(mainBlock!=null) {
-            // the main module cannot contain 'regular' statements (they will never be executed!)
-            for (statement in mainBlock.statements) {
-                val ok = when(statement) {
-                    is Block->true
-                    is Directive->true
-                    is Label->true
-                    is VarDecl->true
-                    is InlineAssembly->true
-                    is INameScope->true
-                    is VariableInitializationAssignment->true
-                    else->false
-                }
-                if(!ok) {
-                    checkResult.add(SyntaxError("main block contains regular statements, this is not allowed (they'll never get executed). Use subroutines.", statement.position))
-                    break
-                }
-            }
-        }
-
-        // there can be an optional 'irq' block with a 'irq' subroutine in it,
-        // which will be used as the 60hz irq routine in the vm if it's present
-        val irqBlock = module.statements.singleOrNull { it is Block && it.name=="irq" } as? Block?
-        val irqSub = irqBlock?.subScopes()?.get("irq") as? Subroutine
-        if(irqSub!=null) {
-            if(irqSub.parameters.isNotEmpty() || irqSub.returntypes.isNotEmpty())
-                checkResult.add(SyntaxError("irq entrypoint subroutine can't have parameters and/or return values", irqSub.position))
-        }
     }
 
     override fun process(returnStmt: Return): IStatement {
@@ -661,7 +672,7 @@ private class AstChecker(private val namespace: INameScope,
         var definingModule = directive.parent
         while (definingModule !is Module)
             definingModule = definingModule.parent
-        if (!(filename.startsWith("library:") || definingModule.importedFrom.resolveSibling(filename).toFile().isFile || File(filename).isFile))
+        if (!(filename.startsWith("library:") || definingModule.source.resolveSibling(filename).toFile().isFile || File(filename).isFile))
             checkResult.add(NameError("included file not found: $filename", directive.position))
     }
 
diff --git a/compiler/src/prog8/ast/AstIdentifiersChecker.kt b/compiler/src/prog8/ast/AstIdentifiersChecker.kt
index 9110eb671..074149ed8 100644
--- a/compiler/src/prog8/ast/AstIdentifiersChecker.kt
+++ b/compiler/src/prog8/ast/AstIdentifiersChecker.kt
@@ -8,9 +8,13 @@ import prog8.functions.BuiltinFunctions
  * Finally, it also makes sure the datatype of all Var decls and sub Return values is set correctly.
  */
 
-fun Module.checkIdentifiers(namespace: INameScope) {
+fun Program.checkIdentifiers() {
     val checker = AstIdentifiersChecker(namespace)
-    this.process(checker)
+    checker.process(this)
+
+    if(modules.map {it.name}.toSet().size != modules.size) {
+        throw FatalAstException("modules should all be unique")
+    }
 
     // add any anonymous variables for heap values that are used,
     // and replace an iterable literalvalue by identifierref to new local variable
@@ -58,6 +62,11 @@ private class AstIdentifiersChecker(private val namespace: INameScope) : IAstPro
         checkResult.add(NameError("name conflict '$name', also defined in ${existing.position.file} line ${existing.position.line}", position))
     }
 
+    override fun process(module: Module) {
+        blocks.clear()  // blocks may be redefined within a different module
+        super.process(module)
+    }
+
     override fun process(block: Block): IStatement {
         val existing = blocks[block.name]
         if(existing!=null)
diff --git a/compiler/src/prog8/ast/AstRecursionChecker.kt b/compiler/src/prog8/ast/AstRecursionChecker.kt
index 3b2714e29..195e67b3d 100644
--- a/compiler/src/prog8/ast/AstRecursionChecker.kt
+++ b/compiler/src/prog8/ast/AstRecursionChecker.kt
@@ -4,9 +4,9 @@ package prog8.ast
  * Checks for the occurrence of recursive subroutine calls
  */
 
-fun Module.checkRecursion(namespace: INameScope) {
+fun Program.checkRecursion() {
     val checker = AstRecursionChecker(namespace)
-    this.process(checker)
+    checker.process(this)
     printErrors(checker.result(), name)
 }
 
diff --git a/compiler/src/prog8/ast/ImportedAstChecker.kt b/compiler/src/prog8/ast/ImportedAstChecker.kt
index 877bd2b17..cf196667d 100644
--- a/compiler/src/prog8/ast/ImportedAstChecker.kt
+++ b/compiler/src/prog8/ast/ImportedAstChecker.kt
@@ -6,9 +6,9 @@ package prog8.ast
  */
 
 fun Module.checkImportedValid() {
-    val checker = ImportedAstChecker()
     this.linkParents()
-    this.process(checker)
+    val checker = ImportedAstChecker()
+    checker.process(this)
     printErrors(checker.result(), name)
 }
 
diff --git a/compiler/src/prog8/ast/StmtReorderer.kt b/compiler/src/prog8/ast/StmtReorderer.kt
index 5b0a65e5d..9b8396ccf 100644
--- a/compiler/src/prog8/ast/StmtReorderer.kt
+++ b/compiler/src/prog8/ast/StmtReorderer.kt
@@ -2,12 +2,12 @@ package prog8.ast
 
 import prog8.compiler.HeapValues
 
-fun Module.reorderStatements(namespace: INameScope, heap: HeapValues) {
+fun Program.reorderStatements() {
     val initvalueCreator = VarInitValueAndAddressOfCreator(namespace)
-    this.process(initvalueCreator)
+    initvalueCreator.process(this)
 
     val checker = StatementReorderer(namespace, heap)
-    this.process(checker)
+    checker.process(this)
 }
 
 const val initvarsSubName="prog8_init_vars"    // the name of the subroutine that should be called for every block to initialize its variables
@@ -42,8 +42,8 @@ private class StatementReorderer(private val namespace: INameScope, private val
             module.statements.removeAt(nonLibBlock.first)
         for(nonLibBlock in nonLibraryBlocks)
             module.statements.add(0, nonLibBlock.second)
-        val mainBlock = module.statements.single { it is Block && it.name=="main" }
-        if((mainBlock as Block).address==null) {
+        val mainBlock = module.statements.singleOrNull { it is Block && it.name=="main" }
+        if(mainBlock!=null && (mainBlock as Block).address==null) {
             module.statements.remove(mainBlock)
             module.statements.add(0, mainBlock)
         }
@@ -103,6 +103,7 @@ private class StatementReorderer(private val namespace: INameScope, private val
         val directives = block.statements.filter {it is Directive && it.directive in directivesToMove}
         block.statements.removeAll(directives)
         block.statements.addAll(0, directives)
+        block.linkParents(block.parent)
 
         sortConstantAssignments(block.statements)
 
diff --git a/compiler/src/prog8/compiler/Compiler.kt b/compiler/src/prog8/compiler/Compiler.kt
index b8d9271c0..6812cda3f 100644
--- a/compiler/src/prog8/compiler/Compiler.kt
+++ b/compiler/src/prog8/compiler/Compiler.kt
@@ -145,11 +145,11 @@ data class CompilationOptions(val output: OutputType,
                               val floats: Boolean)
 
 
-internal class Compiler(private val rootModule: Module,
-                        private val namespace: INameScope,
-                        private val heap: HeapValues): IAstProcessor {
+internal class Compiler(private val programAst2: Program): IAstProcessor {
 
-    val prog: IntermediateProgram = IntermediateProgram(rootModule.name, rootModule.loadAddress, heap, rootModule.importedFrom)
+    val prog: IntermediateProgram = IntermediateProgram(programAst2.name, programAst2.loadAddress, programAst2.heap, programAst2.modules.first().source)
+    val namespace = programAst2.namespace
+    val heap = programAst2.heap
 
     private var generatedLabelSequenceNumber = 0
     private val breakStmtLabelStack : Stack<String> = Stack()
@@ -157,7 +157,9 @@ internal class Compiler(private val rootModule: Module,
 
     fun compile(options: CompilationOptions) : IntermediateProgram {
         println("Creating stackVM code...")
-        process(rootModule)
+        programAst2.modules.forEach {
+            process(it)
+        }
         return prog
     }
 
@@ -218,7 +220,7 @@ internal class Compiler(private val rootModule: Module,
                 is Return -> translate(stmt)
                 is Directive -> {
                     when(stmt.directive) {
-                        "%asminclude" -> translateAsmInclude(stmt.args, prog.importedFrom)
+                        "%asminclude" -> translateAsmInclude(stmt.args, prog.source)
                         "%asmbinary" -> translateAsmBinary(stmt.args)
                         "%breakpoint" -> {
                             prog.line(stmt.position)
@@ -2148,7 +2150,7 @@ internal class Compiler(private val rootModule: Module,
             throw CompilerException("cannot take memory pointer $addrof")
     }
 
-    private fun translateAsmInclude(args: List<DirectiveArg>, importedFrom: Path) {
+    private fun translateAsmInclude(args: List<DirectiveArg>, source: Path) {
         val scopeprefix = if(args[1].str!!.isNotBlank()) "${args[1].str}\t.proc\n" else ""
         val scopeprefixEnd = if(args[1].str!!.isNotBlank()) "\t.pend\n" else ""
         val filename=args[0].str!!
@@ -2158,7 +2160,7 @@ internal class Compiler(private val rootModule: Module,
                     resource.bufferedReader().use { it.readText() }
                 } else {
                     // first try in the same folder as where the containing file was imported from
-                    val sib = importedFrom.resolveSibling(filename)
+                    val sib = source.resolveSibling(filename)
                     if(sib.toFile().isFile)
                         sib.toFile().readText()
                     else
diff --git a/compiler/src/prog8/compiler/intermediate/IntermediateProgram.kt b/compiler/src/prog8/compiler/intermediate/IntermediateProgram.kt
index 4c5b3ee6b..fa3b3cdaa 100644
--- a/compiler/src/prog8/compiler/intermediate/IntermediateProgram.kt
+++ b/compiler/src/prog8/compiler/intermediate/IntermediateProgram.kt
@@ -9,7 +9,7 @@ import java.io.PrintStream
 import java.nio.file.Path
 
 
-class IntermediateProgram(val name: String, var loadAddress: Int, val heap: HeapValues, val importedFrom: Path) {
+class IntermediateProgram(val name: String, var loadAddress: Int, val heap: HeapValues, val source: Path) {
 
     class ProgramBlock(val name: String,
                        var address: Int?,
diff --git a/compiler/src/prog8/optimizing/ConstantFolding.kt b/compiler/src/prog8/optimizing/ConstantFolding.kt
index 75d7a2a15..e0b73aaad 100644
--- a/compiler/src/prog8/optimizing/ConstantFolding.kt
+++ b/compiler/src/prog8/optimizing/ConstantFolding.kt
@@ -9,7 +9,7 @@ import prog8.compiler.target.c64.FLOAT_MAX_POSITIVE
 import kotlin.math.floor
 
 
-class ConstantFolding(private val namespace: INameScope, private val heap: HeapValues) : IAstProcessor {
+class ConstantFolding(private val namespace: GlobalNamespace, private val heap: HeapValues) : IAstProcessor {
     var optimizationsDone: Int = 0
     var errors : MutableList<AstException> = mutableListOf()
 
diff --git a/compiler/src/prog8/optimizing/Extensions.kt b/compiler/src/prog8/optimizing/Extensions.kt
index 776447e1f..4c18ea14a 100644
--- a/compiler/src/prog8/optimizing/Extensions.kt
+++ b/compiler/src/prog8/optimizing/Extensions.kt
@@ -1,48 +1,46 @@
 package prog8.optimizing
 
 import prog8.ast.AstException
-import prog8.ast.INameScope
-import prog8.ast.Module
-import prog8.compiler.HeapValues
+import prog8.ast.Program
 import prog8.parser.ParsingFailedError
 
 
-fun Module.constantFold(globalNamespace: INameScope, heap: HeapValues) {
-    val optimizer = ConstantFolding(globalNamespace, heap)
+fun Program.constantFold() {
+    val optimizer = ConstantFolding(this.namespace, heap)
     try {
-        this.process(optimizer)
+        optimizer.process(this)
     } catch (ax: AstException) {
         optimizer.addError(ax)
     }
 
     while(optimizer.errors.isEmpty() && optimizer.optimizationsDone>0) {
         optimizer.optimizationsDone = 0
-        this.process(optimizer)
+        optimizer.process(this)
     }
 
     if(optimizer.errors.isNotEmpty()) {
         optimizer.errors.forEach { System.err.println(it) }
         throw ParsingFailedError("There are ${optimizer.errors.size} errors.")
     } else {
-        this.linkParents()  // re-link in final configuration
+        modules.forEach { it.linkParents() }   // re-link in final configuration
     }
 }
 
 
-fun Module.optimizeStatements(globalNamespace: INameScope, heap: HeapValues): Int {
-    val optimizer = StatementOptimizer(globalNamespace, heap)
-    this.process(optimizer)
+fun Program.optimizeStatements(): Int {
+    val optimizer = StatementOptimizer(namespace, heap)
+    optimizer.process(this)
     for(stmt in optimizer.statementsToRemove) {
         val scope=stmt.definingScope()
         scope.remove(stmt)
     }
-    this.linkParents()  // re-link in final configuration
+    modules.forEach { it.linkParents() }   // re-link in final configuration
 
     return optimizer.optimizationsDone
 }
 
-fun Module.simplifyExpressions(namespace: INameScope, heap: HeapValues) : Int {
+fun Program.simplifyExpressions() : Int {
     val optimizer = SimplifyExpressions(namespace, heap)
-    this.process(optimizer)
+    optimizer.process(this)
     return optimizer.optimizationsDone
 }
diff --git a/compiler/src/prog8/parser/ModuleParsing.kt b/compiler/src/prog8/parser/ModuleParsing.kt
index 1debf5f63..a7a2d2f7a 100644
--- a/compiler/src/prog8/parser/ModuleParsing.kt
+++ b/compiler/src/prog8/parser/ModuleParsing.kt
@@ -2,22 +2,15 @@ package prog8.parser
 
 import org.antlr.v4.runtime.*
 import prog8.ast.*
-import prog8.compiler.LauncherType
-import prog8.compiler.OutputType
-import prog8.determineCompilationOptions
 import java.io.InputStream
 import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.Paths
-import java.util.*
 
 
 class ParsingFailedError(override var message: String) : Exception(message)
 
 
-private val importedModules : HashMap<String, Module> = hashMapOf()
-
-
 private class LexerErrorListener: BaseErrorListener() {
     var  numberOfErrors: Int = 0
     override fun syntaxError(p0: Recognizer<*, *>?, p1: Any?, p2: Int, p3: Int, p4: String?, p5: RecognitionException?) {
@@ -29,7 +22,33 @@ private class LexerErrorListener: BaseErrorListener() {
 internal class CustomLexer(val modulePath: Path, input: CharStream?) : prog8Lexer(input)
 
 
-fun importModule(stream: CharStream, modulePath: Path, isLibrary: Boolean): Module {
+fun importModule(program: Program, filePath: Path): Module {
+    print("importing '${filePath.fileName}'")
+    if(filePath.parent!=null) {
+        var importloc = filePath.toString()
+        val curdir = Paths.get("").toAbsolutePath().toString()
+        if(importloc.startsWith(curdir))
+            importloc = "." + importloc.substring(curdir.length)
+        println(" (from '$importloc')")
+    }
+    else
+        println("")
+    if(!Files.isReadable(filePath))
+        throw ParsingFailedError("No such file: $filePath")
+
+    val input = CharStreams.fromPath(filePath)
+    val module = importModule(program, input, filePath, filePath.parent==null)
+    return module
+}
+
+fun importLibraryModule(program: Program, name: String): Module? {
+    val import = Directive("%import", listOf(
+            DirectiveArg("", name, 42, position = Position("<<<implicit-import>>>", 0, 0 ,0))
+    ), Position("<<<implicit-import>>>", 0, 0 ,0))
+    return executeImportDirective(program, import, Paths.get(""))
+}
+
+private fun importModule(program: Program, stream: CharStream, modulePath: Path, isLibrary: Boolean): Module {
     val moduleName = modulePath.fileName
     val lexer = CustomLexer(modulePath, stream)
     val lexerErrors = LexerErrorListener()
@@ -46,67 +65,24 @@ fun importModule(stream: CharStream, modulePath: Path, isLibrary: Boolean): Modu
 
     // convert to Ast
     val moduleAst = parseTree.toAst(moduleName.toString(), isLibrary, modulePath)
-    importedModules[moduleAst.name] = moduleAst
+    moduleAst.program = program
+    moduleAst.linkParents()
+    program.modules.add(moduleAst)
 
     // process imports
     val lines = moduleAst.statements.toMutableList()
-    if(!moduleAst.position.file.startsWith("c64utils.") && !moduleAst.isLibraryModule) {
-        // if the output is a PRG or BASIC program, include the c64utils library
-        val compilerOptions = determineCompilationOptions(moduleAst)
-        if(compilerOptions.launcher==LauncherType.BASIC || compilerOptions.output==OutputType.PRG) {
-            lines.add(0, Directive("%import", listOf(DirectiveArg(null, "c64utils", null, moduleAst.position)), moduleAst.position))
-        }
-    }
-    // always import the prog8lib and math compiler libraries
-    if(!moduleAst.position.file.startsWith("math."))
-        lines.add(0, Directive("%import", listOf(DirectiveArg(null, "math", null, moduleAst.position)), moduleAst.position))
-    if(!moduleAst.position.file.startsWith("prog8lib."))
-        lines.add(0, Directive("%import", listOf(DirectiveArg(null, "prog8lib", null, moduleAst.position)), moduleAst.position))
-
-    val imports = lines
-            .asSequence()
-            .mapIndexed { i, it -> Pair(i, it) }
-            .filter { (it.second as? Directive)?.directive == "%import" }
-            .map { Pair(it.first, executeImportDirective(it.second as Directive, modulePath)) }
-            .toList()
-
-    imports.reversed().forEach {
-        if(it.second==null) {
-            // this import was already satisfied. just remove this line.
-            lines.removeAt(it.first)
-        } else {
-            // merge imported lines at this spot
-            lines.addAll(it.first, it.second!!.statements)
-        }
-    }
+    lines.asSequence()
+         .mapIndexed { i, it -> Pair(i, it) }
+         .filter { (it.second as? Directive)?.directive == "%import" }
+         .forEach { executeImportDirective(program, it.second as Directive, modulePath) }
 
     moduleAst.statements = lines
     return moduleAst
 }
 
-
-fun importModule(filePath: Path) : Module {
-    print("importing '${filePath.fileName}'")
-    if(filePath.parent!=null) {
-        var importloc = filePath.toString()
-        val curdir = Paths.get("").toAbsolutePath().toString()
-        if(importloc.startsWith(curdir))
-            importloc = "." + importloc.substring(curdir.length)
-        println(" (from '$importloc')")
-    }
-    else
-        println("")
-    if(!Files.isReadable(filePath))
-        throw ParsingFailedError("No such file: $filePath")
-
-    val input = CharStreams.fromPath(filePath)
-    return importModule(input, filePath, filePath.parent==null)
-}
-
-
-private fun discoverImportedModuleFile(name: String, importedFrom: Path, position: Position?): Path {
+private fun discoverImportedModuleFile(name: String, source: Path, position: Position?): Path {
     val fileName = "$name.p8"
-    val locations = mutableListOf(Paths.get(importedFrom.parent.toString()))
+    val locations = mutableListOf(Paths.get(source.parent.toString()))
 
     val propPath = System.getProperty("prog8.libdir")
     if(propPath!=null)
@@ -124,13 +100,15 @@ private fun discoverImportedModuleFile(name: String, importedFrom: Path, positio
     throw ParsingFailedError("$position Import: no module source file '$fileName' found  (I've looked in: $locations)")
 }
 
-private fun executeImportDirective(import: Directive, importedFrom: Path): Module? {
+private fun executeImportDirective(program: Program, import: Directive, source: Path): Module? {
     if(import.directive!="%import" || import.args.size!=1 || import.args[0].name==null)
         throw SyntaxError("invalid import directive", import.position)
     val moduleName = import.args[0].name!!
     if("$moduleName.p8" == import.position.file)
         throw SyntaxError("cannot import self", import.position)
-    if(importedModules.containsKey(moduleName))
+
+    val existing = program.modules.singleOrNull { it.name == moduleName }
+    if(existing!=null)
         return null
 
     val resource = tryGetEmbeddedResource(moduleName+".p8")
@@ -138,12 +116,14 @@ private fun executeImportDirective(import: Directive, importedFrom: Path): Modul
         if(resource!=null) {
             // load the module from the embedded resource
             resource.use {
+                if(import.args[0].int==42)
+                    print("automatically ")
                 println("importing '$moduleName' (embedded library)")
-                importModule(CharStreams.fromStream(it), Paths.get("@embedded@/$moduleName"), true)
+                importModule(program, CharStreams.fromStream(it), Paths.get("@embedded@/$moduleName"), true)
             }
         } else {
-            val modulePath = discoverImportedModuleFile(moduleName, importedFrom, import.position)
-            importModule(modulePath)
+            val modulePath = discoverImportedModuleFile(moduleName, source, import.position)
+            importModule(program, modulePath)
         }
 
     importedModule.checkImportedValid()