while loop support, and native functions (including ffi!)

ast/src/main/ast/pork.yml

@@ -95,16 +95,18 @@ types:
     - name: arguments
       type: List<Symbol>
     - name: block
-      type: Block
+      type: Block?
+    - name: native
+      type: Native?
   If:
     parent: Expression
     values:
     - name: condition
       type: Expression
-    - name: thenExpression
-      type: Expression
-    - name: elseExpression
-      type: Expression?
+    - name: thenBlock
+      type: Block
+    - name: elseBlock
+      type: Block?
   ImportDeclaration:
     parent: Declaration
     values:
@@ -150,3 +152,23 @@ types:
     values:
     - name: symbol
       type: Symbol
+  While:
+    parent: Expression
+    values:
+    - name: condition
+      type: Expression
+    - name: block
+      type: Block
+  Break:
+    parent: Expression
+    values: []
+  Continue:
+    parent: Expression
+    values: []
+  Native:
+    parent: Node
+    values:
+    - name: form
+      type: Symbol
+    - name: definition
+      type: StringLiteral

ast/src/main/kotlin/gay/pizza/pork/ast/Break.kt

@@ -0,0 +1,22 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("break")
+class Break : Expression() {
+  override val type: NodeType = NodeType.Break
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitBreak(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is Break) return false
+    return true
+  }
+
+  override fun hashCode(): Int =
+    31 * type.hashCode()
+}

ast/src/main/kotlin/gay/pizza/pork/ast/Continue.kt

@@ -0,0 +1,22 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("continue")
+class Continue : Expression() {
+  override val type: NodeType = NodeType.Continue
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitContinue(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is Continue) return false
+    return true
+  }
+
+  override fun hashCode(): Int =
+    31 * type.hashCode()
+}

ast/src/main/kotlin/gay/pizza/pork/ast/FunctionDefinition.kt

@@ -6,18 +6,18 @@ import kotlinx.serialization.Serializable
 
 @Serializable
 @SerialName("functionDefinition")
-class FunctionDefinition(override val modifiers: DefinitionModifiers, override val symbol: Symbol, val arguments: List<Symbol>, val block: Block) : Definition() {
+class FunctionDefinition(override val modifiers: DefinitionModifiers, override val symbol: Symbol, val arguments: List<Symbol>, val block: Block?, val native: Native?) : Definition() {
   override val type: NodeType = NodeType.FunctionDefinition
 
   override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
-    visitor.visitAll(listOf(symbol), arguments, listOf(block))
+    visitor.visitAll(listOf(symbol), arguments, listOf(block), listOf(native))
 
   override fun <T> visit(visitor: NodeVisitor<T>): T =
     visitor.visitFunctionDefinition(this)
 
   override fun equals(other: Any?): Boolean {
     if (other !is FunctionDefinition) return false
-    return other.modifiers == modifiers && other.symbol == symbol && other.arguments == arguments && other.block == block
+    return other.modifiers == modifiers && other.symbol == symbol && other.arguments == arguments && other.block == block && other.native == native
   }
 
   override fun hashCode(): Int {
@@ -25,6 +25,7 @@ class FunctionDefinition(override val modifiers: DefinitionModifiers, override v
     result = 31 * result + symbol.hashCode()
     result = 31 * result + arguments.hashCode()
     result = 31 * result + block.hashCode()
+    result = 31 * result + native.hashCode()
     result = 31 * result + type.hashCode()
     return result
   }

ast/src/main/kotlin/gay/pizza/pork/ast/If.kt

@@ -6,24 +6,24 @@ import kotlinx.serialization.Serializable
 
 @Serializable
 @SerialName("if")
-class If(val condition: Expression, val thenExpression: Expression, val elseExpression: Expression?) : Expression() {
+class If(val condition: Expression, val thenBlock: Block, val elseBlock: Block?) : Expression() {
   override val type: NodeType = NodeType.If
 
   override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
-    visitor.visitNodes(condition, thenExpression, elseExpression)
+    visitor.visitNodes(condition, thenBlock, elseBlock)
 
   override fun <T> visit(visitor: NodeVisitor<T>): T =
     visitor.visitIf(this)
 
   override fun equals(other: Any?): Boolean {
     if (other !is If) return false
-    return other.condition == condition && other.thenExpression == thenExpression && other.elseExpression == elseExpression
+    return other.condition == condition && other.thenBlock == thenBlock && other.elseBlock == elseBlock
   }
 
   override fun hashCode(): Int {
     var result = condition.hashCode()
-    result = 31 * result + thenExpression.hashCode()
-    result = 31 * result + elseExpression.hashCode()
+    result = 31 * result + thenBlock.hashCode()
+    result = 31 * result + elseBlock.hashCode()
     result = 31 * result + type.hashCode()
     return result
   }

ast/src/main/kotlin/gay/pizza/pork/ast/Native.kt

@@ -0,0 +1,29 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("native")
+class Native(val form: Symbol, val definition: StringLiteral) : Node() {
+  override val type: NodeType = NodeType.Native
+
+  override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
+    visitor.visitNodes(form, definition)
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitNative(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is Native) return false
+    return other.form == form && other.definition == definition
+  }
+
+  override fun hashCode(): Int {
+    var result = form.hashCode()
+    result = 31 * result + definition.hashCode()
+    result = 31 * result + type.hashCode()
+    return result
+  }
+}

ast/src/main/kotlin/gay/pizza/pork/ast/NodeCoalescer.kt

@@ -8,9 +8,15 @@ class NodeCoalescer(val handler: (Node) -> Unit) : NodeVisitor<Unit> {
   override fun visitBooleanLiteral(node: BooleanLiteral): Unit =
     handle(node)
 
+  override fun visitBreak(node: Break): Unit =
+    handle(node)
+
   override fun visitCompilationUnit(node: CompilationUnit): Unit =
     handle(node)
 
+  override fun visitContinue(node: Continue): Unit =
+    handle(node)
+
   override fun visitFunctionCall(node: FunctionCall): Unit =
     handle(node)
 
@@ -35,6 +41,9 @@ class NodeCoalescer(val handler: (Node) -> Unit) : NodeVisitor<Unit> {
   override fun visitListLiteral(node: ListLiteral): Unit =
     handle(node)
 
+  override fun visitNative(node: Native): Unit =
+    handle(node)
+
   override fun visitParentheses(node: Parentheses): Unit =
     handle(node)
 
@@ -50,6 +59,9 @@ class NodeCoalescer(val handler: (Node) -> Unit) : NodeVisitor<Unit> {
   override fun visitSymbolReference(node: SymbolReference): Unit =
     handle(node)
 
+  override fun visitWhile(node: While): Unit =
+    handle(node)
+
   fun handle(node: Node) {
     handler(node)
     node.visitChildren(this)

ast/src/main/kotlin/gay/pizza/pork/ast/NodeType.kt

@@ -6,7 +6,9 @@ enum class NodeType(val parent: NodeType? = null) {
   Block(Node),
   Expression(Node),
   BooleanLiteral(Expression),
+  Break(Expression),
   CompilationUnit(Node),
+  Continue(Expression),
   Declaration(Node),
   Definition(Node),
   FunctionCall(Expression),
@@ -17,9 +19,11 @@ enum class NodeType(val parent: NodeType? = null) {
   IntLiteral(Expression),
   LetAssignment(Expression),
   ListLiteral(Expression),
+  Native(Node),
   Parentheses(Expression),
   PrefixOperation(Expression),
   StringLiteral(Expression),
   Symbol(Node),
-  SymbolReference(Expression)
+  SymbolReference(Expression),
+  While(Expression)
 }

ast/src/main/kotlin/gay/pizza/pork/ast/NodeVisitor.kt

@@ -6,8 +6,12 @@ interface NodeVisitor<T> {
 
   fun visitBooleanLiteral(node: BooleanLiteral): T
 
+  fun visitBreak(node: Break): T
+
   fun visitCompilationUnit(node: CompilationUnit): T
 
+  fun visitContinue(node: Continue): T
+
   fun visitFunctionCall(node: FunctionCall): T
 
   fun visitFunctionDefinition(node: FunctionDefinition): T
@@ -24,6 +28,8 @@ interface NodeVisitor<T> {
 
   fun visitListLiteral(node: ListLiteral): T
 
+  fun visitNative(node: Native): T
+
   fun visitParentheses(node: Parentheses): T
 
   fun visitPrefixOperation(node: PrefixOperation): T
@@ -33,4 +39,6 @@ interface NodeVisitor<T> {
   fun visitSymbol(node: Symbol): T
 
   fun visitSymbolReference(node: SymbolReference): T
+
+  fun visitWhile(node: While): T
 }

ast/src/main/kotlin/gay/pizza/pork/ast/NodeVisitorExtensions.kt

@@ -19,10 +19,14 @@ fun <T> NodeVisitor<T>.visit(node: Node): T =
     is PrefixOperation -> visitPrefixOperation(node)
     is StringLiteral -> visitStringLiteral(node)
     is SymbolReference -> visitSymbolReference(node)
+    is While -> visitWhile(node)
+    is Break -> visitBreak(node)
+    is Continue -> visitContinue(node)
+    is Native -> visitNative(node)
   }
 
 fun <T> NodeVisitor<T>.visitNodes(vararg nodes: Node?): List<T> =
   nodes.asSequence().filterNotNull().map { visit(it) }.toList()
 
-fun <T> NodeVisitor<T>.visitAll(vararg nodeLists: List<Node>): List<T> =
-  nodeLists.asSequence().flatten().map { visit(it) }.toList()
+fun <T> NodeVisitor<T>.visitAll(vararg nodeLists: List<Node?>): List<T> =
+  nodeLists.asSequence().flatten().filterNotNull().map { visit(it) }.toList()

ast/src/main/kotlin/gay/pizza/pork/ast/While.kt

@@ -0,0 +1,29 @@
+// GENERATED CODE FROM PORK AST CODEGEN
+package gay.pizza.pork.ast
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+@SerialName("while")
+class While(val condition: Expression, val block: Block) : Expression() {
+  override val type: NodeType = NodeType.While
+
+  override fun <T> visitChildren(visitor: NodeVisitor<T>): List<T> =
+    visitor.visitNodes(condition, block)
+
+  override fun <T> visit(visitor: NodeVisitor<T>): T =
+    visitor.visitWhile(this)
+
+  override fun equals(other: Any?): Boolean {
+    if (other !is While) return false
+    return other.condition == condition && other.block == block
+  }
+
+  override fun hashCode(): Int {
+    var result = condition.hashCode()
+    result = 31 * result + block.hashCode()
+    result = 31 * result + type.hashCode()
+    return result
+  }
+}

buildext/src/main/kotlin/gay/pizza/pork/buildext/ast/AstCodegen.kt

@@ -120,11 +120,12 @@ class AstCodegen(val pkg: String, val outputDirectory: Path, val world: AstWorld
       extensionOf = "NodeVisitor<T>",
       returnType = "List<T>",
       parameters = mutableListOf(
-        KotlinParameter("nodeLists", type = "List<Node>", vararg = true)
+        KotlinParameter("nodeLists", type = "List<Node?>", vararg = true)
       ),
       isImmediateExpression = true
     )
-    visitAllFunction.body.add("nodeLists.asSequence().flatten().map { visit(it) }.toList()")
+    visitAllFunction.body.add(
+      "nodeLists.asSequence().flatten().filterNotNull().map { visit(it) }.toList()")
     visitorExtensionSet.functions.add(visitAllFunction)
 
     write("NodeVisitorExtensions.kt", KotlinWriter(visitorExtensionSet))
@@ -239,16 +240,18 @@ class AstCodegen(val pkg: String, val outputDirectory: Path, val world: AstWorld
       kotlinClassLike.inherits.add("$parentName()")
     }
 
-    for (value in type.values) {
-      val member = KotlinMember(value.name, toKotlinType(value.typeRef))
-      member.abstract = value.abstract
-      if (type.isParentAbstract(value)) {
-        member.overridden = true
+    if (type.values != null) {
+      for (value in type.values!!) {
+        val member = KotlinMember(value.name, toKotlinType(value.typeRef))
+        member.abstract = value.abstract
+        if (type.isParentAbstract(value)) {
+          member.overridden = true
+        }
+        if (role == AstTypeRole.ValueHolder) {
+          member.mutable = true
+        }
+        kotlinClassLike.members.add(member)
       }
-      if (role == AstTypeRole.ValueHolder) {
-        member.mutable = true
-      }
-      kotlinClassLike.members.add(member)
     }
 
     if (role == AstTypeRole.Enum) {
@@ -279,25 +282,26 @@ class AstCodegen(val pkg: String, val outputDirectory: Path, val world: AstWorld
         ),
         isImmediateExpression = true
       )
-      val anyListMembers = type.values.any { it.typeRef.form == AstTypeRefForm.List }
+      val anyListMembers = type.values?.any { it.typeRef.form == AstTypeRefForm.List } ?: false
       val elideVisitChildren: Boolean
       if (anyListMembers) {
-        val visitParameters = type.values.mapNotNull {
+        val visitParameters = (type.values?.mapNotNull {
           if (it.typeRef.primitive != null) {
             null
           } else if (it.typeRef.type != null &&
             !world.typeRegistry.roleOfType(it.typeRef.type).isNodeInherited()) {
             null
-          } else if (it.typeRef.form == AstTypeRefForm.Single) {
+          } else if (it.typeRef.form == AstTypeRefForm.Single ||
+            it.typeRef.form == AstTypeRefForm.Nullable) {
             "listOf(${it.name})"
           } else {
             it.name
           }
-        }.joinToString(", ")
+        } ?: emptyList()).joinToString(", ")
         elideVisitChildren = visitParameters.isEmpty()
         visitChildrenFunction.body.add("visitor.visitAll(${visitParameters})")
       } else {
-        val visitParameters = type.values.mapNotNull {
+        val visitParameters = (type.values?.mapNotNull {
           if (it.typeRef.primitive != null) {
             null
           } else if (it.typeRef.type != null &&
@@ -306,7 +310,7 @@ class AstCodegen(val pkg: String, val outputDirectory: Path, val world: AstWorld
           } else {
             it.name
           }
-        }.joinToString(", ")
+        } ?: emptyList()).joinToString(", ")
         elideVisitChildren = visitParameters.isEmpty()
         visitChildrenFunction.body.add("visitor.visitNodes(${visitParameters})")
       }
@@ -341,9 +345,12 @@ class AstCodegen(val pkg: String, val outputDirectory: Path, val world: AstWorld
         "Any?"
       ))
       equalsFunction.body.add("if (other !is ${type.name}) return false")
-      val predicate = equalsAndHashCodeMembers.mapNotNull {
+      var predicate = equalsAndHashCodeMembers.mapNotNull {
         if (it == "type") null else "other.${it} == $it"
       }.joinToString(" && ")
+      if (predicate.isEmpty()) {
+        predicate = "true"
+      }
       equalsFunction.body.add("return $predicate")
       kotlinClassLike.functions.add(equalsFunction)
 

buildext/src/main/kotlin/gay/pizza/pork/buildext/ast/AstType.kt

@@ -1,17 +1,24 @@
 package gay.pizza.pork.buildext.ast
 
 class AstType(val name: String, var parent: AstType? = null) {
-  private val internalValues = mutableListOf<AstValue>()
+  private var internalValues: MutableList<AstValue>? = null
   private val internalEnums = mutableListOf<AstEnum>()
 
-  val values: List<AstValue>
+  val values: List<AstValue>?
     get() = internalValues
 
   val enums: List<AstEnum>
     get() = internalEnums
 
+  internal fun markHasValues() {
+    if (internalValues == null) {
+      internalValues = mutableListOf()
+    }
+  }
+
   internal fun addValue(value: AstValue) {
-    internalValues.add(value)
+    markHasValues()
+    internalValues!!.add(value)
   }
 
   internal fun addEnum(enum: AstEnum) {
@@ -25,7 +32,7 @@ class AstType(val name: String, var parent: AstType? = null) {
 
     var current = parent
     while (current != null) {
-      val abstract = current.values.firstOrNull {
+      val abstract = current.values?.firstOrNull {
         it.name == value.name && it.abstract
       }
       if (abstract != null) {

buildext/src/main/kotlin/gay/pizza/pork/buildext/ast/AstTypeDescription.kt

@@ -2,6 +2,6 @@ package gay.pizza.pork.buildext.ast
 
 data class AstTypeDescription(
   val parent: String? = null,
-  val values: List<AstValueDescription> = emptyList(),
+  val values: List<AstValueDescription>? = null,
   val enums: List<AstEnumDescription> = emptyList()
 )

buildext/src/main/kotlin/gay/pizza/pork/buildext/ast/AstTypeRegistry.kt

@@ -21,13 +21,14 @@ class AstTypeRegistry {
     when {
       type.enums.isNotEmpty() ->
         AstTypeRole.Enum
-      type.parent == null && type.values.isEmpty() ->
+      type.parent == null && type.values == null ->
         AstTypeRole.RootNode
-      type.parent != null && type.values.all { it.abstract } ->
+      type.parent != null && (type.values == null ||
+        (type.values!!.isNotEmpty() && type.values!!.all { it.abstract })) ->
         AstTypeRole.HierarchyNode
-      type.parent != null && type.values.none { it.abstract } ->
+      type.parent != null && (type.values != null && type.values!!.none { it.abstract }) ->
         AstTypeRole.AstNode
-      type.parent == null && type.values.isNotEmpty() ->
+      type.parent == null && (type.values != null && type.values!!.isNotEmpty()) ->
         AstTypeRole.ValueHolder
       else -> throw RuntimeException("Unable to determine role of type ${type.name}")
   }

buildext/src/main/kotlin/gay/pizza/pork/buildext/ast/AstWorld.kt

@@ -39,10 +39,13 @@ class AstWorld {
           type.parent = world.typeRegistry.lookup(typeDescription.parent)
         }
 
-        for (value in typeDescription.values) {
-          val typeRef = AstTypeRef.parse(value.type, world.typeRegistry)
-          val typeValue = AstValue(value.name, typeRef, abstract = value.required)
-          type.addValue(typeValue)
+        if (typeDescription.values != null) {
+          type.markHasValues()
+          for (value in typeDescription.values) {
+            val typeRef = AstTypeRef.parse(value.type, world.typeRegistry)
+            val typeValue = AstValue(value.name, typeRef, abstract = value.required)
+            type.addValue(typeValue)
+          }
         }
 
         for (enum in typeDescription.enums) {

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

@@ -39,7 +39,7 @@ class CompilationUnitContext(
   }
 
   private fun definitionValue(definition: Definition): Any = when (definition) {
-    is FunctionDefinition -> FunctionContext(definition, internalScope)
+    is FunctionDefinition -> FunctionContext(this, definition)
   }
 
   private fun processAllImports() {

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

@@ -8,6 +8,9 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
   override fun visitIntLiteral(node: IntLiteral): Any = node.value
   override fun visitStringLiteral(node: StringLiteral): Any = node.text
   override fun visitBooleanLiteral(node: BooleanLiteral): Any = node.value
+
+  override fun visitBreak(node: Break): Any = throw BreakMarker
+
   override fun visitListLiteral(node: ListLiteral): Any =
     node.items.map { it.visit(this) }
 
@@ -15,7 +18,8 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
 
   override fun visitFunctionCall(node: FunctionCall): Any {
     val arguments = node.arguments.map { it.visit(this) }
-    return currentScope.call(node.symbol.id, Arguments(arguments))
+    val functionValue = currentScope.value(node.symbol.id) as CallableFunction
+    return functionValue.call(Arguments(arguments))
   }
 
   override fun visitLetAssignment(node: LetAssignment): Any {
@@ -27,6 +31,26 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
   override fun visitSymbolReference(node: SymbolReference): Any =
     currentScope.value(node.symbol.id)
 
+  override fun visitWhile(node: While): Any {
+    val blockFunction = node.block.visit(this) as BlockFunction
+    var result: Any? = null
+    while (true) {
+      val value = node.condition.visit(this)
+      if (value !is Boolean) {
+        throw RuntimeException("While loop attempted on non-boolean value: $value")
+      }
+      if (!value) break
+      try {
+        scoped { result = blockFunction.call() }
+      } catch (_: BreakMarker) {
+        break
+      } catch (_: ContinueMarker) {
+        continue
+      }
+    }
+    return result ?: None
+  }
+
   override fun visitParentheses(node: Parentheses): Any =
     node.expression.visit(this)
 
@@ -45,11 +69,12 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
   override fun visitIf(node: If): Any {
     val condition = node.condition.visit(this)
     return if (condition == true) {
-      node.thenExpression.visit(this)
-    } else {
-      val elseExpression = node.elseExpression
-      elseExpression?.visit(this) ?: None
-    }
+      val blockFunction = node.thenBlock.visit(this) as BlockFunction
+      scoped { blockFunction.call() }
+    } else if (node.elseBlock != null) {
+      val blockFunction = node.elseBlock!!.visit(this) as BlockFunction
+      scoped { blockFunction.call() }
+    } else None
   }
 
   override fun visitInfixOperation(node: InfixOperation): Any {
@@ -93,21 +118,42 @@ class EvaluationVisitor(root: Scope) : NodeVisitor<Any> {
   override fun visitFunctionDefinition(node: FunctionDefinition): Any {
     throw RuntimeException(
       "Function declarations cannot be visited in an EvaluationVisitor. " +
-      "Utilize a FunctionContext."
+        "Utilize a FunctionContext."
     )
   }
 
   override fun visitImportDeclaration(node: ImportDeclaration): Any {
     throw RuntimeException(
       "Import declarations cannot be visited in an EvaluationVisitor. " +
-      "Utilize an EvaluationContext."
+        "Utilize an CompilationUnitContext."
     )
   }
 
   override fun visitCompilationUnit(node: CompilationUnit): Any {
     throw RuntimeException(
       "Compilation units cannot be visited in an EvaluationVisitor. " +
-        "Utilize an EvaluationContext."
+        "Utilize an CompilationUnitContext."
     )
   }
+
+  override fun visitNative(node: Native): Any {
+    throw RuntimeException(
+      "Native definition cannot be visited in an EvaluationVisitor. " +
+        "Utilize an FunctionContext."
+    )
+  }
+
+  override fun visitContinue(node: Continue): Any = ContinueMarker
+
+  private inline fun <T> scoped(block: () -> T): T {
+    currentScope = currentScope.fork()
+    try {
+      return block()
+    } finally {
+      currentScope = currentScope.leave()
+    }
+  }
+
+  private object BreakMarker : RuntimeException("Break Marker")
+  private object ContinueMarker: RuntimeException("Continue Marker")
 }

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

@@ -4,6 +4,7 @@ import gay.pizza.pork.frontend.World
 
 class Evaluator(val world: World, val scope: Scope) {
   private val contexts = mutableMapOf<String, CompilationUnitContext>()
+  private val nativeFunctionProviders = mutableMapOf<String, NativeFunctionProvider>()
 
   fun evaluate(path: String): Scope =
     context(path).externalScope
@@ -17,4 +18,13 @@ class Evaluator(val world: World, val scope: Scope) {
     context.initIfNeeded()
     return context
   }
+
+  fun nativeFunctionProvider(form: String): NativeFunctionProvider {
+    return nativeFunctionProviders[form] ?:
+      throw RuntimeException("Unknown native function form: $form")
+  }
+
+  fun addNativeFunctionProvider(form: String, nativeFunctionProvider: NativeFunctionProvider) {
+    nativeFunctionProviders[form] = nativeFunctionProvider
+  }
 }

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

@@ -2,14 +2,27 @@ package gay.pizza.pork.evaluator
 
 import gay.pizza.pork.ast.FunctionDefinition
 
-class FunctionContext(val node: FunctionDefinition, val internalScope: Scope) : CallableFunction {
+class FunctionContext(val compilationUnitContext: CompilationUnitContext, val node: FunctionDefinition) : CallableFunction {
   override fun call(arguments: Arguments): Any {
-    val scope = internalScope.fork()
+    val scope = compilationUnitContext.internalScope.fork()
     for ((index, argumentSymbol) in node.arguments.withIndex()) {
       scope.define(argumentSymbol.id, arguments.values[index])
     }
+
+    if (node.native != null) {
+      val native = node.native!!
+      val nativeFunctionProvider =
+        compilationUnitContext.evaluator.nativeFunctionProvider(native.form.id)
+      val nativeFunction = nativeFunctionProvider.provideNativeFunction(native.definition.text)
+      return nativeFunction.call(arguments)
+    }
+
+    if (node.block == null) {
+      throw RuntimeException("Native or Block is required for FunctionDefinition")
+    }
+
     val visitor = EvaluationVisitor(scope)
-    val blockFunction = visitor.visitBlock(node.block)
+    val blockFunction = visitor.visitBlock(node.block!!)
     return blockFunction.call()
   }
 }

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

@@ -0,0 +1,5 @@
+package gay.pizza.pork.evaluator
+
+interface NativeFunctionProvider {
+  fun provideNativeFunction(definition: String): CallableFunction
+}

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

@@ -41,27 +41,19 @@ class Scope(val parent: Scope? = null, inherits: List<Scope> = emptyList()) {
     return value
   }
 
-  fun call(name: String, arguments: Arguments): Any {
-    val value = value(name)
-    if (value !is CallableFunction) {
-      throw RuntimeException("$value is not callable")
-    }
-    return value.call(arguments)
-  }
-
   fun fork(): Scope =
     Scope(this)
 
-  fun leave(): Scope {
-    if (parent == null) {
-      throw RuntimeException("Parent context not found")
-    }
-    return parent
-  }
-
   internal fun inherit(scope: Scope) {
     inherited.add(scope)
   }
 
+  fun leave(): Scope {
+    if (parent == null) {
+      throw RuntimeException("Attempted to leave the root scope!")
+    }
+    return parent
+  }
+
   private object NotFound
 }

examples/ffi.pork

@@ -0,0 +1,13 @@
+func malloc(size)
+  native ffi "libc.dylib:malloc:void*"
+
+func free(pointer)
+  native ffi "libc.dylib:free:void"
+
+export func main() {
+  while true {
+    let pointer = malloc(8192)
+    println(pointer)
+    free(pointer)
+  }
+}

examples/fib.pork

@@ -1,10 +1,14 @@
 /* fibonacci sequence */
 func fib(n) {
-  if n == 0
-    then 0
-  else if n == 1
-    then 1
-  else fib(n - 1) + fib(n - 2)
+  if n == 0 {
+    0
+  } else {
+    if n == 1 {
+      1
+    } else {
+      fib(n - 1) + fib(n - 2)
+    }
+  }
 }
 
 export func main() {

examples/loop.pork

@@ -0,0 +1,6 @@
+export func main() {
+  while true {
+    println("Hello World")
+    break
+  }
+}

ffi/build.gradle.kts

@@ -0,0 +1,10 @@
+plugins {
+  id("gay.pizza.pork.module")
+}
+
+dependencies {
+  api(project(":evaluator"))
+
+  implementation(project(":common"))
+  implementation("net.java.dev.jna:jna:5.13.0")
+}

ffi/src/main/kotlin/gay/pizza/pork/ffi/JnaNativeProvider.kt

@@ -0,0 +1,26 @@
+package gay.pizza.pork.ffi
+
+import com.sun.jna.Function
+import gay.pizza.pork.evaluator.CallableFunction
+import gay.pizza.pork.evaluator.NativeFunctionProvider
+
+class JnaNativeProvider : NativeFunctionProvider {
+  override fun provideNativeFunction(definition: String): CallableFunction {
+    val (libraryName, functionSymbol, returnType, _) =
+      definition.split(":", limit = 3)
+    val function = Function.getFunction(libraryName, functionSymbol)
+    return CallableFunction {
+      return@CallableFunction invoke(function, it.values.toTypedArray(), returnType)
+    }
+  }
+
+  private fun invoke(function: Function, values: Array<Any>, type: String): Any = when (type) {
+    "void*" -> function.invokePointer(values)
+    "int" -> function.invokeInt(values)
+    "long" -> function.invokeLong(values)
+    "float" -> function.invokeFloat(values)
+    "double" -> function.invokeDouble(values)
+    "void" -> function.invokeVoid(values)
+    else -> throw RuntimeException("Unsupported ffi return type: $type")
+  }
+}

parser/src/main/kotlin/gay/pizza/pork/parser/Parser.kt

@@ -72,13 +72,26 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
   private fun readIf(): If = within {
     expect(TokenType.If)
     val condition = readExpression()
-    expect(TokenType.Then)
-    val thenExpression = readExpression()
-    var elseExpression: Expression? = null
+    val thenBlock = readBlock()
+    var elseBlock: Block? = null
     if (next(TokenType.Else)) {
-      elseExpression = readExpression()
+      elseBlock = readBlock()
     }
-    If(condition, thenExpression, elseExpression)
+    If(condition, thenBlock, elseBlock)
+  }
+
+  private fun readWhile(): While = within {
+    expect(TokenType.While)
+    val condition = readExpression()
+    val block = readBlock()
+    While(condition, block)
+  }
+
+  private fun readNative(): Native = within {
+    expect(TokenType.Native)
+    val form = readSymbolRaw()
+    val definition = readStringLiteral()
+    Native(form, definition)
   }
 
   fun readExpression(): Expression {
@@ -120,6 +133,20 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
         readIf()
       }
 
+      TokenType.While -> {
+        readWhile()
+      }
+
+      TokenType.Break -> {
+        expect(TokenType.Break)
+        Break()
+      }
+
+      TokenType.Continue -> {
+        expect(TokenType.Continue)
+        Continue()
+      }
+
       else -> {
         throw RuntimeException(
           "Failed to parse token: ${token.type} '${token.text}' as" +
@@ -178,7 +205,15 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
       readSymbolRaw()
     }
     expect(TokenType.RightParentheses)
-    FunctionDefinition(modifiers, name, arguments, readBlock())
+
+    var native: Native? = null
+    var block: Block? = null
+    if (peek(TokenType.Native)) {
+      native = readNative()
+    } else {
+      block = readBlock()
+    }
+    FunctionDefinition(modifiers, name, arguments, block, native)
   }
 
   private fun maybeReadDefinition(): Definition? {

parser/src/main/kotlin/gay/pizza/pork/parser/Printer.kt

@@ -38,6 +38,8 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
     }
   }
 
+  override fun visitBreak(node: Break): Unit = append("break")
+
   override fun visitListLiteral(node: ListLiteral) {
     append("[")
     if (node.items.isNotEmpty()) {
@@ -55,6 +57,13 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
     append("]")
   }
 
+  override fun visitNative(node: Native) {
+    append("native ")
+    visit(node.form)
+    append(" ")
+    visit(node.definition)
+  }
+
   override fun visitSymbol(node: Symbol) {
     append(node.id)
   }
@@ -82,6 +91,13 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
     visit(node.symbol)
   }
 
+  override fun visitWhile(node: While) {
+    append("while ")
+    visit(node.condition)
+    append(" ")
+    visit(node.block)
+  }
+
   override fun visitParentheses(node: Parentheses) {
     append("(")
     visit(node.expression)
@@ -96,18 +112,13 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
   override fun visitIf(node: If) {
     append("if ")
     visit(node.condition)
-    append(" then")
-    out.increaseIndent()
-    appendLine()
-    visit(node.thenExpression)
-    out.decreaseIndent()
-    if (node.elseExpression != null) {
-      appendLine()
+    append(" ")
+    visit(node.thenBlock)
+    if (node.elseBlock != null) {
+      append(" ")
       append("else")
-      out.increaseIndent()
-      appendLine()
-      visit(node.elseExpression!!)
-      out.decreaseIndent()
+      append(" ")
+      visit(node.elseBlock!!)
     }
   }
 
@@ -120,7 +131,7 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
   }
 
   override fun visitFunctionDefinition(node: FunctionDefinition) {
-    append("fn ")
+    append("func ")
     visit(node.symbol)
     append("(")
     for ((index, argument) in node.arguments.withIndex()) {
@@ -130,7 +141,13 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
       }
     }
     append(") ")
-    visit(node.block)
+    if (node.block != null) {
+      visit(node.block!!)
+    }
+
+    if (node.native != null) {
+      visit(node.native!!)
+    }
   }
 
   override fun visitBlock(node: Block) {
@@ -167,4 +184,6 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
       appendLine()
     }
   }
+
+  override fun visitContinue(node: Continue): Unit = append("continue")
 }

parser/src/main/kotlin/gay/pizza/pork/parser/TokenType.kt

@@ -25,11 +25,14 @@ enum class TokenType(vararg properties: TokenTypeProperty) {
   False(Keyword("false"), KeywordFamily),
   True(Keyword("true"), KeywordFamily),
   If(Keyword("if"), KeywordFamily),
-  Then(Keyword("then"), KeywordFamily),
   Else(Keyword("else"), KeywordFamily),
+  While(Keyword("while"), KeywordFamily),
+  Continue(Keyword("continue"), KeywordFamily),
+  Break(Keyword("break"), KeywordFamily),
   Import(Keyword("import"), KeywordFamily),
   Export(Keyword("export"), KeywordFamily),
   Func(Keyword("func"), KeywordFamily),
+  Native(Keyword("native"), KeywordFamily),
   Let(Keyword("let"), KeywordFamily),
   Whitespace(CharConsumer { it == ' ' || it == '\r' || it == '\n' || it == '\t' }),
   BlockComment(CommentFamily),

settings.gradle.kts

@@ -8,16 +8,6 @@ include(
   ":parser",
   ":frontend",
   ":evaluator",
+  ":ffi",
   ":tool"
 )
-
-dependencyResolutionManagement {
-  versionCatalogs {
-    create("libs") {
-      version("clikt", "4.2.0")
-
-      library("clikt", "com.github.ajalt.clikt", "clikt")
-        .versionRef("clikt")
-    }
-  }
-}

tool/build.gradle.kts

@@ -10,7 +10,8 @@ dependencies {
   api(project(":parser"))
   api(project(":frontend"))
   api(project(":evaluator"))
-  implementation(libs.clikt)
+  api(project(":ffi"))
+  api("com.github.ajalt.clikt:clikt:4.2.0")
   implementation(project(":common"))
 }
 

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

@@ -5,9 +5,11 @@ import com.github.ajalt.clikt.parameters.arguments.argument
 import com.github.ajalt.clikt.parameters.options.flag
 import com.github.ajalt.clikt.parameters.options.option
 import gay.pizza.dough.fs.PlatformFsProvider
+import gay.pizza.pork.evaluator.Arguments
 import gay.pizza.pork.evaluator.CallableFunction
 import gay.pizza.pork.evaluator.None
 import gay.pizza.pork.evaluator.Scope
+import gay.pizza.pork.ffi.JnaNativeProvider
 
 class RunCommand : CliktCommand(help = "Run Program", name = "run") {
   val loop by option("--loop", help = "Loop Program").flag()
@@ -28,8 +30,12 @@ class RunCommand : CliktCommand(help = "Run Program", name = "run") {
       None
     })
 
+    val main = tool.loadMainFunction(scope, setupEvaluator = {
+      addNativeFunctionProvider("ffi", JnaNativeProvider())
+    })
+
     maybeLoopAndMeasure(loop, measure) {
-      tool.evaluate(scope)
+      main.call(Arguments(emptyList()))
     }
   }
 }

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

@@ -5,6 +5,7 @@ import gay.pizza.pork.parser.Printer
 import gay.pizza.pork.ast.CompilationUnit
 import gay.pizza.pork.ast.visit
 import gay.pizza.pork.evaluator.Arguments
+import gay.pizza.pork.evaluator.CallableFunction
 import gay.pizza.pork.evaluator.Evaluator
 import gay.pizza.pork.evaluator.Scope
 import gay.pizza.pork.frontend.ContentSource
@@ -29,11 +30,12 @@ abstract class Tool {
 
   fun <T> visit(visitor: NodeVisitor<T>): T = visitor.visit(parse())
 
-  fun evaluate(scope: Scope) {
+  fun loadMainFunction(scope: Scope, setupEvaluator: Evaluator.() -> Unit = {}): CallableFunction {
     val contentSource = createContentSource()
     val world = World(contentSource)
     val evaluator = Evaluator(world, scope)
+    setupEvaluator(evaluator)
     val resultingScope = evaluator.evaluate(rootFilePath())
-    resultingScope.call("main", Arguments(emptyList()))
+    return resultingScope.value("main") as CallableFunction
   }
 }