language: implement for in

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

@@ -106,6 +106,15 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
     While(condition, block)
   }
 
+  private fun readForIn(): ForIn = within {
+    expect(TokenType.For)
+    val symbol = readSymbolRaw()
+    expect(TokenType.In)
+    val value = readExpression()
+    val block = readBlock()
+    ForIn(symbol, value, block)
+  }
+
   private fun readNative(): Native = within {
     expect(TokenType.Native)
     val form = readSymbolRaw()
@@ -160,6 +169,10 @@ class Parser(source: PeekableSource<Token>, val attribution: NodeAttribution) {
         readWhile()
       }
 
+      TokenType.For -> {
+        readForIn()
+      }
+
       TokenType.Break -> {
         expect(TokenType.Break)
         Break()

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

@@ -28,6 +28,15 @@ class Printer(buffer: StringBuilder) : NodeVisitor<Unit> {
     append(node.value.toString())
   }
 
+  override fun visitForIn(node: ForIn) {
+    append("for ")
+    visit(node.symbol)
+    append(" in ")
+    visit(node.expression)
+    append(" ")
+    visit(node.block)
+  }
+
   override fun visitStringLiteral(node: StringLiteral) {
     append("\"")
     append(StringEscape.escape(node.text))

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

@@ -47,6 +47,8 @@ enum class TokenType(vararg properties: TokenTypeProperty) {
   If(ManyChars("if"), KeywordFamily),
   Else(ManyChars("else"), KeywordFamily),
   While(ManyChars("while"), KeywordFamily),
+  For(ManyChars("for"), KeywordFamily),
+  In(ManyChars("in"), KeywordFamily),
   Continue(ManyChars("continue"), KeywordFamily),
   Break(ManyChars("break"), KeywordFamily),
   Import(ManyChars("import"), KeywordFamily),