evaluator: functions now use their own evaluation visitor

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationContext.kt

@@ -8,18 +8,16 @@ class EvaluationContext(
   val evaluationContextProvider: EvaluationContextProvider,
   rootScope: Scope
 ) {
-  private var isAlreadySetup = false
-
   val internalRootScope = rootScope.fork()
   val externalRootScope = rootScope.fork()
 
-  private val evaluationVisitor = EvaluationVisitor(internalRootScope)
+  private var initialized = false
 
-  fun setup() {
-    if (isAlreadySetup) {
+  fun init() {
+    if (initialized) {
       return
     }
-    isAlreadySetup = true
+    initialized = true
     val imports = compilationUnit.declarations.filterIsInstance<ImportDeclaration>()
     for (import in imports) {
       val evaluationContext = evaluationContextProvider.provideEvaluationContext(import.path.text)
@@ -27,10 +25,13 @@ class EvaluationContext(
     }
 
     for (definition in compilationUnit.definitions) {
+      val evaluationVisitor = EvaluationVisitor(internalRootScope)
       evaluationVisitor.visit(definition)
-      if (definition.modifiers.export) {
-        externalRootScope.define(definition.symbol.id, internalRootScope.value(definition.symbol.id))
+      if (!definition.modifiers.export) {
+        continue
       }
+      val internalValue = internalRootScope.value(definition.symbol.id)
+      externalRootScope.define(definition.symbol.id, internalValue)
     }
   }
 }

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/EvaluationVisitor.kt

@@ -102,18 +102,14 @@ class EvaluationVisitor(val root: Scope) : NodeVisitor<Any> {
   }
 
   override fun visitFunctionDefinition(node: FunctionDefinition): Any {
-    val blockFunction = visitBlock(node.block) as BlockFunction
     val function = CallableFunction { arguments ->
-      val formerScope = currentScope
       currentScope = root.fork()
       for ((index, argumentSymbol) in node.arguments.withIndex()) {
         currentScope.define(argumentSymbol.id, arguments.values[index])
       }
-      try {
-        return@CallableFunction blockFunction.call()
-      } finally {
-        currentScope = formerScope
-      }
+      val visitor = EvaluationVisitor(currentScope)
+      val blockFunction = visitor.visitBlock(node.block) as BlockFunction
+      return@CallableFunction blockFunction.call()
     }
     currentScope.define(node.symbol.id, function)
     return None

evaluator/src/main/kotlin/gay/pizza/pork/evaluator/Evaluator.kt

@@ -16,7 +16,7 @@ class Evaluator(val world: World, val scope: Scope) : EvaluationContextProvider
     val context = contexts.computeIfAbsent(identity) {
       EvaluationContext(unit, this, scope)
     }
-    context.setup()
+    context.init()
     return context
   }
 }