Implement interface types.

frog/leg/typechecker.dart

Index: frog/leg/typechecker.dart
diff --git a/frog/leg/typechecker.dart b/frog/leg/typechecker.dart
index db4df503ea0f19cd4eb389d2dac58664ff90be25..bd5d8ae2e8355c63d4df76448036196a5e3bff7b 100644
--- a/frog/leg/typechecker.dart
+++ b/frog/leg/typechecker.dart
@@ -48,12 +48,36 @@ class StatementType implements Type {
   String toString() => stringName;
 }
 
-class SimpleType implements Type {
+class TypeVariable {

[ahe, 2012/02/29 12:49:15]

What is the purpose of this class?

[karlklose, 2012/03/30 11:56:40]

Removed.

   final SourceString name;
-  final Element element;
+  final Type value;

[ahe, 2012/02/29 12:49:15]

What is this?

[karlklose, 2012/03/30 11:56:40]

Removed the class.

+  const TypeVariable(this.name, [this.value]);
+}

[ngeoffray, 2012/02/24 13:36:15]

You can remove the code above.

[karlklose, 2012/03/30 11:56:40]

Done.

 
-  const SimpleType(SourceString this.name, Element this.element);
+class InterfaceType implements Type {
+  final SourceString name;
+  final ClassElement element;
+  final Link<Type> arguments;
+  const InterfaceType(SourceString this.name, ClassElement this.element,
+                      [Link<Type> arguments = const EmptyLink<Type>()])

[ahe, 2012/02/29 12:49:15]

Why not this.arguments?

[karlklose, 2012/03/30 11:56:40]

Done.

+    : this.arguments = arguments;

[ngeoffray, 2012/02/24 13:36:15]

Add new line.

[ngeoffray, 2012/02/24 13:36:15]

Do you think it'd be more robust to write:
this.arguments = arguments == null ? const EmptyLink<Type>() : arguments;

Instead of giving a default value to arguments?

[karlklose, 2012/03/30 11:56:40]

Done.

+  toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.add(name);
+    bool first = true;
+    for (Link link = arguments; !link.isEmpty(); link = link.tail) {

[ahe, 2012/02/29 12:49:15]

Could you use:
if (!arguments.isEmpty()) {
  sb.add('<');
  arguments.printOn(sb, ', ')
  sb.add('>');
}

[karlklose, 2012/03/30 11:56:40]

Done.

+      sb.add(first ? '<' : ', ');
+      sb.add(link.head);
+      if (link.tail.isEmpty()) sb.add('>');
+      first = false;
+    }
+    return sb.toString();
+  }
+}
 
+// TODO(karlklose): merge into InterfaceType as a named constructor.

[ahe, 2012/02/29 12:49:15]

+1

+class SimpleType extends InterfaceType {
+  const SimpleType(SourceString name, Element element) : super(name, element);
   String toString() => name.toString();
 }