vm: a functional virtual machine, mostly

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/CompiledWorld.kt

@@ -6,5 +6,6 @@ import kotlinx.serialization.Serializable
 data class CompiledWorld(
   val constantPool: ConstantPool,
   val symbolTable: SymbolTable,
-  val code: List<Op>
+  val code: List<Op>,
+  val annotations: List<OpAnnotation>
 )

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/Constant.kt

@@ -1,3 +1,21 @@
 package gay.pizza.pork.bytecode
 
-class Constant(val id: UInt, val value: ByteArray)
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class Constant(val id: UInt, val tag: ConstantTag, val value: ByteArray) {
+  override fun equals(other: Any?): Boolean {
+    if (this === other) return true
+    other as Constant
+
+    if (id != other.id) return false
+    if (!value.contentEquals(other.value)) return false
+    return true
+  }
+
+  override fun hashCode(): Int {
+    var result = id.hashCode()
+    result = 31 * result + value.contentHashCode()
+    return result
+  }
+}

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/ConstantPool.kt

@@ -3,4 +3,4 @@ package gay.pizza.pork.bytecode
 import kotlinx.serialization.Serializable
 
 @Serializable
-data class ConstantPool(val constants: List<ByteArray>)
+data class ConstantPool(val constants: List<Constant>)

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/ConstantTag.kt

@@ -0,0 +1,8 @@
+package gay.pizza.pork.bytecode
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+enum class ConstantTag {
+  String
+}

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/MutableConstantPool.kt

@@ -3,16 +3,16 @@ package gay.pizza.pork.bytecode
 class MutableConstantPool {
   private val pool = mutableListOf<Constant>()
 
-  fun assign(content: ByteArray): UInt {
+  fun assign(tag: ConstantTag, content: ByteArray): UInt {
     for (constant in pool) {
-      if (constant.value.contentEquals(content)) {
+      if (constant.value.contentEquals(content) && tag == constant.tag) {
         return constant.id
       }
     }
     val id = pool.size.toUInt()
-    pool.add(Constant(id, content))
+    pool.add(Constant(id = id, tag = tag, value = content))
     return id
   }
 
-  fun all(): List<Constant> = pool
+  fun build(): ConstantPool = ConstantPool(pool)
 }

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/OpAnnotation.kt

@@ -0,0 +1,6 @@
+package gay.pizza.pork.bytecode
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class OpAnnotation(val inst: UInt, val text: String)

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/Opcode.kt

@@ -30,14 +30,16 @@ enum class Opcode(val id: UByte) {
   BinaryAnd(28u),
   BinaryOr(29u),
   BinaryXor(30u),
-  List(31u),
-  Integer(32u),
-  Double(33u),
-  Call(34u),
-  EuclideanModulo(35u),
-  Remainder(36u),
-  Index(37u),
-  ScopeIn(38u),
-  ScopeOut(39u),
+  ListMake(31u),
+  ListSize(32u),
+  Integer(33u),
+  Double(34u),
+  Call(35u),
+  EuclideanModulo(36u),
+  Remainder(37u),
+  Index(38u),
+  ScopeIn(39u),
+  ScopeOut(40u),
+  ReturnAddress(41u),
   End(255u),
 }

bytecode/src/main/kotlin/gay/pizza/pork/bytecode/SymbolTable.kt

@@ -5,4 +5,13 @@ import kotlinx.serialization.Serializable
 @Serializable
 data class SymbolTable(
   val symbols: List<SymbolInfo>
-)
+) {
+  fun lookup(inst: UInt): Pair<SymbolInfo, UInt>? {
+    val symbol = symbols.firstOrNull {
+      (inst >= it.offset) && inst < (it.offset + it.size)
+    } ?: return null
+
+    val rel = inst - symbol.offset
+    return symbol to rel
+  }
+}

compiler/src/main/kotlin/gay/pizza/pork/compiler/CodeBuilder.kt

@@ -6,6 +6,7 @@ import gay.pizza.pork.bytecode.Opcode
 
 class CodeBuilder(val symbol: CompilableSymbol) {
   private val ops = mutableListOf<StubOp>()
+  private val annotations = mutableListOf<StubOpAnnotation>()
 
   val localState: LocalState = LocalState(symbol)
 
@@ -39,5 +40,9 @@ class CodeBuilder(val symbol: CompilableSymbol) {
     ops.add(PatchSymOp(Op(code, arguments), patches))
   }
 
-  fun build(): List<StubOp> = ops.toList()
+  fun annotate(text: String) {
+    annotations.add(StubOpAnnotation(symbol, nextOpInst(), text))
+  }
+
+  fun build(): CompiledSymbolResult = CompiledSymbolResult(ops.toList(), annotations.toList())
 }

compiler/src/main/kotlin/gay/pizza/pork/compiler/CompilableSymbol.kt

@@ -6,12 +6,12 @@ import gay.pizza.pork.ast.gen.visit
 import gay.pizza.pork.frontend.scope.ScopeSymbol
 
 class CompilableSymbol(val compilableSlab: CompilableSlab, val scopeSymbol: ScopeSymbol) {
-  val compiledStubOps: List<StubOp> by lazy { compile() }
+  val compiledStubOps: CompiledSymbolResult by lazy { compile() }
 
   val usedSymbols: List<ScopeSymbol>
     get() = scopeSymbol.scope.usedSymbols
 
-  private fun compile(): List<StubOp> {
+  private fun compile(): CompiledSymbolResult {
     val emitter = StubOpEmitter(compilableSlab.compiler, this)
     emitter.enter()
     val what = if (scopeSymbol.definition is FunctionDefinition) {

compiler/src/main/kotlin/gay/pizza/pork/compiler/CompiledSymbolResult.kt

@@ -0,0 +1,3 @@
+package gay.pizza.pork.compiler
+
+class CompiledSymbolResult(val ops: List<StubOp>, val annotations: List<StubOpAnnotation>)

compiler/src/main/kotlin/gay/pizza/pork/compiler/CompiledWorldLayout.kt

@@ -4,13 +4,16 @@ import gay.pizza.pork.bytecode.*
 
 class CompiledWorldLayout(val compiler: Compiler) : StubResolutionContext {
   private val allStubOps = mutableListOf<StubOp>()
+  private val allStubAnnotations = mutableListOf<StubOpAnnotation>()
   private val symbolTable = mutableMapOf<CompilableSymbol, SymbolInfo>()
 
   fun add(symbol: CompilableSymbol) {
     val start = allStubOps.size
-    val stubOps = symbol.compiledStubOps
+    val result = symbol.compiledStubOps
+    val stubOps = result.ops
     symbolTable[symbol] = SymbolInfo(symbol.id, start.toUInt(), stubOps.size.toUInt())
     allStubOps.addAll(stubOps)
+    allStubAnnotations.addAll(result.annotations)
   }
 
   private fun patch(): List<Op> {
@@ -23,16 +26,24 @@ class CompiledWorldLayout(val compiler: Compiler) : StubResolutionContext {
     return ops
   }
 
+  private fun patchAnnotations(): List<OpAnnotation> {
+    val annotations = mutableListOf<OpAnnotation>()
+    for (stub in allStubAnnotations) {
+      val actual = symbolTable[stub.symbol]!!.offset + stub.rel
+      annotations.add(OpAnnotation(actual, stub.text))
+    }
+    return annotations
+  }
+
   override fun resolveJumpTarget(symbol: CompilableSymbol): UInt {
     return symbolTable[symbol]?.offset ?:
       throw RuntimeException("Unable to resolve jump target: ${symbol.scopeSymbol.symbol.id}")
   }
 
-  fun layoutCompiledWorld(): CompiledWorld {
-    val constantPool = mutableListOf<ByteArray>()
-    for (item in compiler.constantPool.all()) {
-      constantPool.add(item.value)
-    }
-    return CompiledWorld(ConstantPool(constantPool), SymbolTable(symbolTable.values.toList()), patch())
-  }
+  fun build(): CompiledWorld = CompiledWorld(
+    constantPool = compiler.constantPool.build(),
+    symbolTable = SymbolTable(symbolTable.values.toList()),
+    code = patch(),
+    annotations = patchAnnotations()
+  )
 }

compiler/src/main/kotlin/gay/pizza/pork/compiler/Compiler.kt

@@ -42,6 +42,6 @@ class Compiler {
     for (used in usedSymbolSet) {
       layout.add(used)
     }
-    return layout.layoutCompiledWorld()
+    return layout.build()
   }
 }

compiler/src/main/kotlin/gay/pizza/pork/compiler/LocalState.kt

@@ -31,6 +31,13 @@ class LocalState(val symbol: CompilableSymbol) {
     return variable
   }
 
+  fun createAnonymousLocal(): StubVar {
+    val scope = variables.last()
+    val variable = StubVar(localVarIndex++)
+    scope.add(variable)
+    return variable
+  }
+
   fun pushScope() {
     variables.add(mutableListOf())
   }

compiler/src/main/kotlin/gay/pizza/pork/compiler/StubOpAnnotation.kt

@@ -0,0 +1,3 @@
+package gay.pizza.pork.compiler
+
+data class StubOpAnnotation(val symbol: CompilableSymbol, val rel: UInt, val text: String)

compiler/src/main/kotlin/gay/pizza/pork/compiler/StubOpEmitter.kt

@@ -2,11 +2,12 @@ package gay.pizza.pork.compiler
 
 import gay.pizza.pork.ast.FunctionLevelVisitor
 import gay.pizza.pork.ast.gen.*
+import gay.pizza.pork.bytecode.ConstantTag
 import gay.pizza.pork.bytecode.MutableRel
 import gay.pizza.pork.bytecode.Opcode
 
 class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : FunctionLevelVisitor<Unit>() {
-  val code = CodeBuilder(symbol)
+  val code: CodeBuilder = CodeBuilder(symbol)
 
   fun allocateOuterScope(definition: FunctionDefinition) {
     val allNormalArguments = definition.arguments.takeWhile { !it.multiple }
@@ -55,7 +56,35 @@ class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : Func
   }
 
   override fun visitForIn(node: ForIn) {
-    TODO("ForIn is currently unsupported")
+    val listLocalVar = code.localState.createAnonymousLocal()
+    val sizeLocalVar = code.localState.createAnonymousLocal()
+    val currentIndexVar = code.localState.createAnonymousLocal()
+    val currentValueVar = code.localState.createLocal(node.item.symbol)
+    node.expression.visit(this)
+    code.emit(Opcode.StoreLocal, listOf(listLocalVar.index))
+    load(Loadable(stubVar = listLocalVar))
+    code.emit(Opcode.ListSize)
+    code.emit(Opcode.StoreLocal, listOf(sizeLocalVar.index))
+    code.emit(Opcode.Integer, listOf(0u))
+    code.emit(Opcode.StoreLocal, listOf(currentIndexVar.index))
+    val endOfLoop = MutableRel(0u)
+    val startOfLoop = code.nextOpInst()
+    code.localState.startLoop(startOfLoop, endOfLoop)
+    load(Loadable(stubVar = currentIndexVar))
+    load(Loadable(stubVar = sizeLocalVar))
+    code.emit(Opcode.CompareGreaterEqual)
+    code.patch(Opcode.JumpIf, listOf(0u), 0, symbol, endOfLoop)
+    load(Loadable(stubVar = currentIndexVar))
+    load(Loadable(stubVar = listLocalVar))
+    code.emit(Opcode.Index)
+    code.emit(Opcode.StoreLocal, listOf(currentValueVar.index))
+    node.block.visit(this)
+    code.emit(Opcode.LoadLocal, listOf(currentIndexVar.index))
+    code.emit(Opcode.Integer, listOf(1u))
+    code.emit(Opcode.Add)
+    code.emit(Opcode.StoreLocal, listOf(currentIndexVar.index))
+    code.patch(Opcode.Jump, listOf(0u), 0, symbol, startOfLoop)
+    endOfLoop.rel = code.nextOpInst()
   }
 
   override fun visitFunctionCall(node: FunctionCall) {
@@ -64,10 +93,12 @@ class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : Func
     val targetSymbol = compiler.resolve(targetScopeSymbol)
     val functionDefinition = targetSymbol.scopeSymbol.definition as FunctionDefinition
     val retRel = MutableRel(0u)
-    code.patch(Opcode.Integer, listOf(0u), 0, symbol, retRel)
-
     val normalArguments = mutableListOf<Expression>()
     var variableArguments: List<Expression>? = null
+    if (functionDefinition.arguments.any { it.multiple }) {
+      variableArguments = emptyList()
+    }
+
     for ((index, item) in functionDefinition.arguments.zip(node.arguments).withIndex()) {
       val (spec, value) = item
       if (spec.multiple) {
@@ -83,14 +114,15 @@ class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : Func
       for (item in variableArguments.reversed()) {
         item.visit(this)
       }
-      code.emit(Opcode.List, listOf(variableArguments.size.toUInt()))
+      code.emit(Opcode.ListMake, listOf(variableArguments.size.toUInt()))
     }
 
     for (item in normalArguments.reversed()) {
       visit(item)
     }
 
-    retRel.rel = code.nextOpInst() + 1u
+    retRel.rel = code.nextOpInst() + 2u
+    code.patch(Opcode.ReturnAddress, listOf(0u), 0, symbol, retRel)
     code.patch(Opcode.Call, listOf(0u), mapOf(0 to targetSymbol))
   }
 
@@ -154,7 +186,7 @@ class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : Func
     for (item in node.items) {
       item.visit(this)
     }
-    code.emit(Opcode.List, listOf(count.toUInt()))
+    code.emit(Opcode.ListMake, listOf(count.toUInt()))
   }
 
   override fun visitLongLiteral(node: LongLiteral) {
@@ -190,7 +222,7 @@ class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : Func
 
   override fun visitStringLiteral(node: StringLiteral) {
     val bytes = node.text.toByteArray()
-    val constant = compiler.constantPool.assign(bytes)
+    val constant = compiler.constantPool.assign(ConstantTag.String, bytes)
     code.emit(Opcode.Constant, listOf(constant))
   }
 
@@ -243,10 +275,10 @@ class StubOpEmitter(val compiler: Compiler, val symbol: CompilableSymbol) : Func
 
   override fun visitNativeFunctionDescriptor(node: NativeFunctionDescriptor) {
     for (def in node.definitions) {
-      val defConstant = compiler.constantPool.assign(def.text.toByteArray())
+      val defConstant = compiler.constantPool.assign(ConstantTag.String, def.text.toByteArray())
       code.emit(Opcode.Constant, listOf(defConstant))
     }
-    val formConstant = compiler.constantPool.assign(node.form.id.toByteArray())
+    val formConstant = compiler.constantPool.assign(ConstantTag.String, node.form.id.toByteArray())
     code.emit(Opcode.Native, listOf(formConstant, node.definitions.size.toUInt()))
   }
 

compiler/src/main/kotlin/gay/pizza/pork/compiler/StubVar.kt

@@ -4,5 +4,5 @@ import gay.pizza.pork.ast.gen.Symbol
 
 class StubVar(
   val index: UInt,
-  val symbol: Symbol
+  val symbol: Symbol? = null
 )

support/pork-idea/src/main/kotlin/gay/pizza/pork/idea/psi/gen/NativeFunctionDescriptorElement.kt

@@ -6,7 +6,7 @@ import com.intellij.navigation.ItemPresentation
 import gay.pizza.pork.idea.psi.PorkElementHelpers
 import javax.swing.Icon
 
-class NativeElement(node: ASTNode) : PorkElement(node) {
+class NativeFunctionDescriptorElement(node: ASTNode) : PorkElement(node) {
   override fun getIcon(flags: Int): Icon? =
     PorkElementHelpers.iconOf(this)
 

support/pork-idea/src/main/kotlin/gay/pizza/pork/idea/psi/gen/PorkElementFactory.kt

@@ -40,7 +40,7 @@ object PorkElementFactory {
       NodeType.Break -> BreakElement(node)
       NodeType.Continue -> ContinueElement(node)
       NodeType.NoneLiteral -> NoneLiteralElement(node)
-      NodeType.Native -> NativeElement(node)
+      NodeType.NativeFunctionDescriptor -> NativeFunctionDescriptorElement(node)
       NodeType.IndexedBy -> IndexedByElement(node)
       else -> ASTWrapperPsiElement(node)
     }

tool/src/main/kotlin/gay/pizza/pork/tool/CompileCommand.kt

@@ -24,7 +24,12 @@ class CompileCommand : CliktCommand(help = "Compile Pork to Bytecode", name = "c
       val code = compiledWorld.code.subList(symbol.offset.toInt(), (symbol.offset + symbol.size).toInt())
       println(symbol.id)
       for ((index, op) in code.withIndex()) {
-        println("  ${symbol.offset + index.toUInt()} ${op.code.name} ${op.args.joinToString(" ")}")
+        var annotation = ""
+        val annotations = compiledWorld.annotations.filter { it.inst == (symbol.offset + index.toUInt()) }
+        if (annotations.isNotEmpty()) {
+          annotation = " ; ${annotations.joinToString(", ") { it.text}}"
+        }
+        println("  ${symbol.offset + index.toUInt()} ${op.code.name} ${op.args.joinToString(" ")}${annotation}")
       }
     }
     val vm = VirtualMachine(compiledWorld)

tool/src/main/kotlin/gay/pizza/pork/tool/ScopeAnalysisCommand.kt

@@ -20,7 +20,7 @@ class ScopeAnalysisCommand : CliktCommand(help = "Run Scope Analysis", name = "s
         "symbol ${visibleScopeSymbol.scopeSymbol.symbol.id} " +
         "type=${visibleScopeSymbol.scopeSymbol.definition.type.name} " +
         "internal=${visibleScopeSymbol.isInternalSymbol} " +
-        "slab=${visibleScopeSymbol.scopeSymbol.slab.location.commonFriendlyName}"
+        "slab=${visibleScopeSymbol.scopeSymbol.slabScope.slab.location.commonFriendlyName}"
       )
     }
   }

vm/src/main/kotlin/gay/pizza/pork/vm/InternalMachine.kt

@@ -1,6 +1,7 @@
 package gay.pizza.pork.vm
 
 import gay.pizza.pork.bytecode.CompiledWorld
+import gay.pizza.pork.bytecode.ConstantTag
 
 class InternalMachine(val world: CompiledWorld, val handlers: List<OpHandler>) {
   private val inlined = world.code.map { op ->
@@ -10,10 +11,12 @@ class InternalMachine(val world: CompiledWorld, val handlers: List<OpHandler>) {
   }
 
   private var inst: UInt = 0u
-  private val stack = mutableListOf<Any>(EndOfCode)
+  private val stack = mutableListOf<Any>()
   private val locals = mutableListOf<MutableMap<UInt, Any>>(
     mutableMapOf()
   )
+  private val callStack = mutableListOf(0u)
+  private val returnAddressStack = mutableListOf<UInt>()
   private var autoNextInst = true
   private var exitFlag = false
 
@@ -36,7 +39,11 @@ class InternalMachine(val world: CompiledWorld, val handlers: List<OpHandler>) {
   }
 
   fun loadConstant(id: UInt) {
-    push(world.constantPool.constants[id.toInt()])
+    val constant = world.constantPool.constants[id.toInt()]
+    when (constant.tag) {
+      ConstantTag.String -> push(String(constant.value))
+      else -> throw VirtualMachineException("Unknown Constant Tag: ${constant.tag.name}")
+    }
   }
 
   fun loadLocal(id: UInt) {
@@ -48,7 +55,7 @@ class InternalMachine(val world: CompiledWorld, val handlers: List<OpHandler>) {
 
   fun storeLocal(id: UInt) {
     val localSet = locals.last()
-    val value = pop()
+    val value = popAnyValue()
     localSet[id] = value
   }
 
@@ -57,24 +64,47 @@ class InternalMachine(val world: CompiledWorld, val handlers: List<OpHandler>) {
     autoNextInst = false
   }
 
+  fun pushReturnAddress(value: UInt) {
+    returnAddressStack.add(value)
+  }
+
+  fun pushCallStack(value: UInt) {
+    callStack.add(value)
+  }
+
+  fun popCallStack() {
+    callStack.removeLast()
+  }
+
+  fun armReturnAddressIfSet() {
+    val returnAddress = returnAddressStack.removeLastOrNull()
+    if (returnAddress != null) {
+      setNextInst(returnAddress)
+    } else {
+      exit()
+    }
+  }
+
   fun push(item: Any) {
     stack.add(item)
   }
 
-  fun pop(): Any = stack.removeLast()
+  fun popAnyValue(): Any = stack.removeLast()
+
+  inline fun <reified T> pop(): T = popAnyValue() as T
+
   fun exit() {
     exitFlag = true
   }
 
   fun reset() {
     stack.clear()
-    stack.add(EndOfCode)
+    callStack.clear()
+    callStack.add(0u)
     locals.clear()
     locals.add(mutableMapOf())
     inst = 0u
     exitFlag = false
     autoNextInst = true
   }
-
-  data object EndOfCode
 }

vm/src/main/kotlin/gay/pizza/pork/vm/VirtualMachine.kt

@@ -12,10 +12,18 @@ class VirtualMachine(world: CompiledWorld) : ExecutionContext {
     TrueOpHandler,
     FalseOpHandler,
 
-    ListOpHandler,
+    ListMakeOpHandler,
+    ListSizeOpHandler,
+
+    IndexOpHandler,
+
+    AndOpHandler,
+    OrOpHandler,
+    NotOpHandler,
 
     CompareEqualOpHandler,
     CompareLesserEqualOpHandler,
+    CompareGreaterEqualOpHandler,
 
     AddOpHandler,
 
@@ -25,13 +33,16 @@ class VirtualMachine(world: CompiledWorld) : ExecutionContext {
     LoadLocalOpHandler,
     StoreLocalOpHandler,
 
+    ReturnAddressOpHandler,
     CallOpHandler,
-    RetOpHandler,
+    ReturnOpHandler,
 
     NativeOpHandler,
 
     ScopeInOpHandler,
-    ScopeOutOpHandler
+    ScopeOutOpHandler,
+
+    EndOpHandler
   ))
 
   override fun execute() {

vm/src/main/kotlin/gay/pizza/pork/vm/ops/AddOpHandler.kt

@@ -4,16 +4,11 @@ import gay.pizza.pork.bytecode.Op
 import gay.pizza.pork.bytecode.Opcode
 import gay.pizza.pork.vm.InternalMachine
 import gay.pizza.pork.vm.OpHandler
-import gay.pizza.pork.vm.VirtualMachineException
 
 object AddOpHandler : OpHandler(Opcode.Add) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val left = machine.pop()
-    val right = machine.pop()
-
-    if (left !is Int || right !is Int) {
-      throw VirtualMachineException("Bad types.")
-    }
+    val left = machine.pop<Int>()
+    val right = machine.pop<Int>()
     machine.push(left + right)
   }
 }

vm/src/main/kotlin/gay/pizza/pork/vm/ops/AndOpHandler.kt

@@ -0,0 +1,14 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object AndOpHandler : OpHandler(Opcode.And) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    val left = machine.pop<Boolean>()
+    val right = machine.pop<Boolean>()
+    machine.push(left && right)
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/CallOpHandler.kt

@@ -8,6 +8,7 @@ import gay.pizza.pork.vm.OpHandler
 object CallOpHandler : OpHandler(Opcode.Call) {
   override fun handle(machine: InternalMachine, op: Op) {
     machine.setNextInst(op.args[0])
+    machine.pushCallStack(op.args[0])
     machine.pushScope()
   }
 }

vm/src/main/kotlin/gay/pizza/pork/vm/ops/CompareEqualOpHandler.kt

@@ -7,6 +7,6 @@ import gay.pizza.pork.vm.OpHandler
 
 object CompareEqualOpHandler : OpHandler(Opcode.CompareEqual) {
   override fun handle(machine: InternalMachine, op: Op) {
-    machine.push(machine.pop() == machine.pop())
+    machine.push(machine.popAnyValue() == machine.popAnyValue())
   }
 }

vm/src/main/kotlin/gay/pizza/pork/vm/ops/CompareGreaterEqualOpHandler.kt

@@ -0,0 +1,14 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object CompareGreaterEqualOpHandler : OpHandler(Opcode.CompareGreaterEqual) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    val right = machine.pop<Int>()
+    val left = machine.pop<Int>()
+    machine.push(left >= right)
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/CompareLesserEqualOpHandler.kt

@@ -4,16 +4,11 @@ import gay.pizza.pork.bytecode.Op
 import gay.pizza.pork.bytecode.Opcode
 import gay.pizza.pork.vm.InternalMachine
 import gay.pizza.pork.vm.OpHandler
-import gay.pizza.pork.vm.VirtualMachineException
 
 object CompareLesserEqualOpHandler : OpHandler(Opcode.CompareLesserEqual) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val right = machine.pop()
-    val left = machine.pop()
-
-    if (left !is Int || right !is Int) {
-      throw VirtualMachineException("Bad types.")
-    }
+    val right = machine.pop<Int>()
+    val left = machine.pop<Int>()
     machine.push(left <= right)
   }
 }

vm/src/main/kotlin/gay/pizza/pork/vm/ops/EndOpHandler.kt

@@ -0,0 +1,12 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object EndOpHandler : OpHandler(Opcode.End) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    machine.exit()
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/IndexOpHandler.kt

@@ -0,0 +1,14 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object IndexOpHandler : OpHandler(Opcode.Index) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    val list = machine.pop<List<*>>()
+    val index = machine.pop<Number>().toInt()
+    machine.push(list[index] as Any)
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/JumpIfOpHandler.kt

@@ -8,11 +8,7 @@ import gay.pizza.pork.vm.VirtualMachineException
 
 object JumpIfOpHandler : OpHandler(Opcode.JumpIf) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val value = machine.pop()
-    if (value !is Boolean) {
-      throw VirtualMachineException("JumpIf expects a boolean value on the stack.")
-    }
-
+    val value = machine.pop<Boolean>()
     if (value) {
       machine.setNextInst(op.args[0])
     }

vm/src/main/kotlin/gay/pizza/pork/vm/ops/ListMakeOpHandler.kt

@@ -5,12 +5,12 @@ import gay.pizza.pork.bytecode.Opcode
 import gay.pizza.pork.vm.InternalMachine
 import gay.pizza.pork.vm.OpHandler
 
-object ListOpHandler : OpHandler(Opcode.List) {
+object ListMakeOpHandler : OpHandler(Opcode.ListMake) {
   override fun handle(machine: InternalMachine, op: Op) {
     val count = op.args[0]
     val list = mutableListOf<Any>()
     for (i in 1u..count) {
-      val item = machine.pop()
+      val item = machine.popAnyValue()
       list.add(item)
     }
     machine.push(list.reversed())

vm/src/main/kotlin/gay/pizza/pork/vm/ops/ListSizeOpHandler.kt

@@ -0,0 +1,13 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object ListSizeOpHandler : OpHandler(Opcode.ListSize) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    val list = machine.pop<List<*>>()
+    machine.push(list.size)
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/NativeOpHandler.kt

@@ -10,7 +10,7 @@ object NativeOpHandler : OpHandler(Opcode.Native) {
     val countOfNativeDefs = op.args[1].toInt()
     val defs = mutableListOf<Any>()
     for (i in 0 until countOfNativeDefs) {
-      defs.add(String(machine.pop() as ByteArray))
+      defs.add(machine.pop() as String)
     }
   }
 }

vm/src/main/kotlin/gay/pizza/pork/vm/ops/NotOpHandler.kt

@@ -0,0 +1,12 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object NotOpHandler : OpHandler(Opcode.Not) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    machine.push(!machine.pop<Boolean>())
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/OrOpHandler.kt

@@ -0,0 +1,14 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object OrOpHandler : OpHandler(Opcode.Or) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    val left = machine.pop<Boolean>()
+    val right = machine.pop<Boolean>()
+    machine.push(left || right)
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/ReturnAddressOpHandler.kt

@@ -0,0 +1,12 @@
+package gay.pizza.pork.vm.ops
+
+import gay.pizza.pork.bytecode.Op
+import gay.pizza.pork.bytecode.Opcode
+import gay.pizza.pork.vm.InternalMachine
+import gay.pizza.pork.vm.OpHandler
+
+object ReturnAddressOpHandler : OpHandler(Opcode.ReturnAddress) {
+  override fun handle(machine: InternalMachine, op: Op) {
+    machine.pushReturnAddress(op.args[0])
+  }
+}

vm/src/main/kotlin/gay/pizza/pork/vm/ops/ReturnOpHandler.kt

@@ -5,14 +5,10 @@ import gay.pizza.pork.bytecode.Opcode
 import gay.pizza.pork.vm.InternalMachine
 import gay.pizza.pork.vm.OpHandler
 
-object RetOpHandler : OpHandler(Opcode.Return) {
+object ReturnOpHandler : OpHandler(Opcode.Return) {
   override fun handle(machine: InternalMachine, op: Op) {
-    val last = machine.pop()
-    if (last == InternalMachine.EndOfCode) {
-      machine.exit()
-      return
-    }
     machine.popScope()
-    machine.setNextInst((last as Int).toUInt())
+    machine.armReturnAddressIfSet()
+    machine.popCallStack()
   }
 }