global: a working virtual machine for some of the use cases. APIs and validation still WIP.

execution/src/main/kotlin/gay/pizza/pork/execution/ArgumentList.kt

@@ -0,0 +1,5 @@
+package gay.pizza.pork.execution
+
+typealias ArgumentList = List<Any>
+
+inline fun <reified T> ArgumentList.at(index: Int): T = this[index] as T

execution/src/main/kotlin/gay/pizza/pork/execution/ExecutionContextProvider.kt

@@ -4,5 +4,5 @@ import gay.pizza.pork.ast.gen.Symbol
 import gay.pizza.pork.frontend.ImportLocator
 
 interface ExecutionContextProvider {
-  fun prepare(importLocator: ImportLocator, entryPointSymbol: Symbol): ExecutionContext
+  fun prepare(importLocator: ImportLocator, entryPointSymbol: Symbol, nativeRegistry: NativeRegistry): ExecutionContext
 }

execution/src/main/kotlin/gay/pizza/pork/execution/InternalNativeProvider.kt

@@ -0,0 +1,45 @@
+package gay.pizza.pork.execution
+
+class InternalNativeProvider(val quiet: Boolean = false) : NativeProvider {
+  private val functions = mutableMapOf(
+    "print" to NativeFunction(::printValues),
+    "println" to NativeFunction(::printLine),
+    "listSet" to NativeFunction(::setInList),
+    "listInitWith" to NativeFunction(::listInitWith)
+  )
+
+  fun add(name: String, function: NativeFunction) {
+    functions[name] = function
+  }
+
+  override fun provideNativeFunction(definitions: List<String>): NativeFunction {
+    val definition = definitions[0]
+    return functions[definition] ?:
+      throw RuntimeException("Unknown internal function: $definition")
+  }
+
+  private fun printValues(arguments: ArgumentList): Any {
+    if (quiet || arguments.isEmpty()) return None
+    print(arguments.at<List<*>>(0).joinToString(" ") { it.toString() })
+    return None
+  }
+
+  private fun printLine(arguments: ArgumentList): Any {
+    if (quiet) return None
+    println(arguments.at<List<*>>(0).joinToString(" ") { it.toString() })
+    return Unit
+  }
+
+  private fun setInList(arguments: ArgumentList): Any {
+    @Suppress("UNCHECKED_CAST")
+    val list = arguments[0] as MutableList<Any>
+    val value = arguments[2]
+    list[(arguments.at<Number>(0)).toInt()] = value
+    return value
+  }
+
+  private fun listInitWith(arguments: ArgumentList): Any {
+    val size = arguments.at<Number>(0).toInt()
+    return MutableList(size) { arguments[1] }
+  }
+}

execution/src/main/kotlin/gay/pizza/pork/execution/NativeFunction.kt

@@ -0,0 +1,5 @@
+package gay.pizza.pork.execution
+
+fun interface NativeFunction {
+  fun invoke(args: ArgumentList): Any
+}

execution/src/main/kotlin/gay/pizza/pork/execution/NativeProvider.kt

@@ -0,0 +1,5 @@
+package gay.pizza.pork.execution
+
+interface NativeProvider {
+  fun provideNativeFunction(definitions: List<String>): NativeFunction
+}

execution/src/main/kotlin/gay/pizza/pork/execution/NativeRegistry.kt

@@ -0,0 +1,18 @@
+package gay.pizza.pork.execution
+
+class NativeRegistry {
+  private val providers = mutableMapOf<String, NativeProvider>()
+
+  fun add(form: String, provider: NativeProvider) {
+    providers[form] = provider
+  }
+
+  fun forEachProvider(block: (String, NativeProvider) -> Unit) {
+    for ((form, provider) in providers) {
+      block(form, provider)
+    }
+  }
+
+  fun of(form: String): NativeProvider =
+    providers[form] ?: throw RuntimeException("Unknown native form: ${form}")
+}

execution/src/main/kotlin/gay/pizza/pork/execution/None.kt

@@ -0,0 +1,3 @@
+package gay.pizza.pork.execution
+
+data object None