diff --git a/modules/angular2/src/change_detection/parser/ast.ts b/modules/angular2/src/change_detection/parser/ast.ts
index 7de3a9a5f3..46bdb522eb 100644
--- a/modules/angular2/src/change_detection/parser/ast.ts
+++ b/modules/angular2/src/change_detection/parser/ast.ts
@@ -8,7 +8,7 @@ export class AST {
 
   assign(context, locals, value) { throw new BaseException("Not supported"); }
 
-  visit(visitor): any { return null; }
+  visit(visitor: AstVisitor): any { return null; }
 
   toString(): string { return "AST"; }
 }
@@ -16,7 +16,7 @@ export class AST {
 export class EmptyExpr extends AST {
   eval(context, locals) { return null; }
 
-  visit(visitor) {
+  visit(visitor: AstVisitor) {
     // do nothing
   }
 }
@@ -24,7 +24,7 @@ export class EmptyExpr extends AST {
 export class ImplicitReceiver extends AST {
   eval(context, locals) { return context; }
 
-  visit(visitor) { return visitor.visitImplicitReceiver(this); }
+  visit(visitor: AstVisitor) { return visitor.visitImplicitReceiver(this); }
 }
 
 /**
@@ -42,7 +42,7 @@ export class Chain extends AST {
     return result;
   }
 
-  visit(visitor) { return visitor.visitChain(this); }
+  visit(visitor: AstVisitor) { return visitor.visitChain(this); }
 }
 
 export class Conditional extends AST {
@@ -56,7 +56,7 @@ export class Conditional extends AST {
     }
   }
 
-  visit(visitor) { return visitor.visitConditional(this); }
+  visit(visitor: AstVisitor) { return visitor.visitConditional(this); }
 }
 
 export class AccessMember extends AST {
@@ -88,7 +88,7 @@ export class AccessMember extends AST {
     }
   }
 
-  visit(visitor) { return visitor.visitAccessMember(this); }
+  visit(visitor: AstVisitor) { return visitor.visitAccessMember(this); }
 }
 
 export class SafeAccessMember extends AST {
@@ -102,7 +102,7 @@ export class SafeAccessMember extends AST {
     return isBlank(evaluatedReceiver) ? null : this.getter(evaluatedReceiver);
   }
 
-  visit(visitor) { return visitor.visitSafeAccessMember(this); }
+  visit(visitor: AstVisitor) { return visitor.visitSafeAccessMember(this); }
 }
 
 export class KeyedAccess extends AST {
@@ -123,7 +123,7 @@ export class KeyedAccess extends AST {
     return value;
   }
 
-  visit(visitor) { return visitor.visitKeyedAccess(this); }
+  visit(visitor: AstVisitor) { return visitor.visitKeyedAccess(this); }
 }
 
 export class Pipe extends AST {
@@ -132,7 +132,7 @@ export class Pipe extends AST {
     super();
   }
 
-  visit(visitor) { return visitor.visitPipe(this); }
+  visit(visitor: AstVisitor) { return visitor.visitPipe(this); }
 }
 
 export class LiteralPrimitive extends AST {
@@ -140,7 +140,7 @@ export class LiteralPrimitive extends AST {
 
   eval(context, locals) { return this.value; }
 
-  visit(visitor) { return visitor.visitLiteralPrimitive(this); }
+  visit(visitor: AstVisitor) { return visitor.visitLiteralPrimitive(this); }
 }
 
 export class LiteralArray extends AST {
@@ -150,7 +150,7 @@ export class LiteralArray extends AST {
     return ListWrapper.map(this.expressions, (e) => e.eval(context, locals));
   }
 
-  visit(visitor) { return visitor.visitLiteralArray(this); }
+  visit(visitor: AstVisitor) { return visitor.visitLiteralArray(this); }
 }
 
 export class LiteralMap extends AST {
@@ -164,7 +164,7 @@ export class LiteralMap extends AST {
     return res;
   }
 
-  visit(visitor) { return visitor.visitLiteralMap(this); }
+  visit(visitor: AstVisitor) { return visitor.visitLiteralMap(this); }
 }
 
 export class Interpolation extends AST {
@@ -172,7 +172,7 @@ export class Interpolation extends AST {
 
   eval(context, locals) { throw new BaseException("evaluating an Interpolation is not supported"); }
 
-  visit(visitor) { visitor.visitInterpolation(this); }
+  visit(visitor: AstVisitor) { visitor.visitInterpolation(this); }
 }
 
 export class Binary extends AST {
@@ -223,7 +223,7 @@ export class Binary extends AST {
     throw 'Internal error [$operation] not handled';
   }
 
-  visit(visitor) { return visitor.visitBinary(this); }
+  visit(visitor: AstVisitor) { return visitor.visitBinary(this); }
 }
 
 export class PrefixNot extends AST {
@@ -231,7 +231,7 @@ export class PrefixNot extends AST {
 
   eval(context, locals) { return !this.expression.eval(context, locals); }
 
-  visit(visitor) { return visitor.visitPrefixNot(this); }
+  visit(visitor: AstVisitor) { return visitor.visitPrefixNot(this); }
 }
 
 export class Assignment extends AST {
@@ -241,7 +241,7 @@ export class Assignment extends AST {
     return this.target.assign(context, locals, this.value.eval(context, locals));
   }
 
-  visit(visitor) { return visitor.visitAssignment(this); }
+  visit(visitor: AstVisitor) { return visitor.visitAssignment(this); }
 }
 
 export class MethodCall extends AST {
@@ -262,7 +262,7 @@ export class MethodCall extends AST {
     }
   }
 
-  visit(visitor) { return visitor.visitMethodCall(this); }
+  visit(visitor: AstVisitor) { return visitor.visitMethodCall(this); }
 }
 
 export class SafeMethodCall extends AST {
@@ -278,7 +278,7 @@ export class SafeMethodCall extends AST {
     return this.fn(evaluatedReceiver, evaluatedArgs);
   }
 
-  visit(visitor) { return visitor.visitSafeMethodCall(this); }
+  visit(visitor: AstVisitor) { return visitor.visitSafeMethodCall(this); }
 }
 
 export class FunctionCall extends AST {
@@ -292,7 +292,7 @@ export class FunctionCall extends AST {
     return FunctionWrapper.apply(obj, evalList(context, locals, this.args));
   }
 
-  visit(visitor) { return visitor.visitFunctionCall(this); }
+  visit(visitor: AstVisitor) { return visitor.visitFunctionCall(this); }
 }
 
 export class ASTWithSource extends AST {
@@ -304,7 +304,7 @@ export class ASTWithSource extends AST {
 
   assign(context, locals, value) { return this.ast.assign(context, locals, value); }
 
-  visit(visitor) { return this.ast.visit(visitor); }
+  visit(visitor: AstVisitor) { return this.ast.visit(visitor); }
 
   toString(): string { return `${this.source} in ${this.location}`; }
 }
@@ -314,27 +314,27 @@ export class TemplateBinding {
               public expression: ASTWithSource) {}
 }
 
-// INTERFACE
-export class AstVisitor {
-  visitAccessMember(ast: AccessMember) {}
-  visitAssignment(ast: Assignment) {}
-  visitBinary(ast: Binary) {}
-  visitChain(ast: Chain) {}
-  visitConditional(ast: Conditional) {}
-  visitPipe(ast: Pipe) {}
-  visitFunctionCall(ast: FunctionCall) {}
-  visitImplicitReceiver(ast: ImplicitReceiver) {}
-  visitKeyedAccess(ast: KeyedAccess) {}
-  visitLiteralArray(ast: LiteralArray) {}
-  visitLiteralMap(ast: LiteralMap) {}
-  visitLiteralPrimitive(ast: LiteralPrimitive) {}
-  visitMethodCall(ast: MethodCall) {}
-  visitPrefixNot(ast: PrefixNot) {}
-  visitSafeAccessMember(ast: SafeAccessMember) {}
-  visitSafeMethodCall(ast: SafeMethodCall) {}
+export interface AstVisitor {
+  visitAccessMember(ast: AccessMember): any;
+  visitAssignment(ast: Assignment): any;
+  visitBinary(ast: Binary): any;
+  visitChain(ast: Chain): any;
+  visitConditional(ast: Conditional): any;
+  visitPipe(ast: Pipe): any;
+  visitFunctionCall(ast: FunctionCall): any;
+  visitImplicitReceiver(ast: ImplicitReceiver): any;
+  visitInterpolation(ast: Interpolation): any;
+  visitKeyedAccess(ast: KeyedAccess): any;
+  visitLiteralArray(ast: LiteralArray): any;
+  visitLiteralMap(ast: LiteralMap): any;
+  visitLiteralPrimitive(ast: LiteralPrimitive): any;
+  visitMethodCall(ast: MethodCall): any;
+  visitPrefixNot(ast: PrefixNot): any;
+  visitSafeAccessMember(ast: SafeAccessMember): any;
+  visitSafeMethodCall(ast: SafeMethodCall): any;
 }
 
-export class AstTransformer {
+export class AstTransformer implements AstVisitor {
   visitImplicitReceiver(ast: ImplicitReceiver) { return ast; }
 
   visitInterpolation(ast: Interpolation) {
@@ -393,6 +393,10 @@ export class AstTransformer {
     }
     return res;
   }
+
+  visitChain(ast: Chain) { throw new BaseException('Not implemented'); }
+
+  visitAssignment(ast: Assignment) { throw new BaseException('Not implemented'); }
 }
 
 var _evalListCache = [
diff --git a/modules/angular2/src/change_detection/proto_change_detector.ts b/modules/angular2/src/change_detection/proto_change_detector.ts
index e951df5de9..540594cb3e 100644
--- a/modules/angular2/src/change_detection/proto_change_detector.ts
+++ b/modules/angular2/src/change_detection/proto_change_detector.ts
@@ -122,7 +122,6 @@ class ProtoRecordBuilder {
 
   _appendRecords(b: BindingRecord, variableNames: List<string>) {
     if (b.isDirectiveLifecycle()) {
-      ;
       ListWrapper.push(
           this.records,
           new ProtoRecord(RECORD_TYPE_DIRECTIVE_LIFECYCLE, b.lifecycleEvent, null, [], [], -1, null,
@@ -133,7 +132,7 @@ class ProtoRecordBuilder {
   }
 }
 
-class _ConvertAstIntoProtoRecords {
+class _ConvertAstIntoProtoRecords implements AstVisitor {
   constructor(private _records: List<ProtoRecord>, private _bindingRecord: BindingRecord,
               private _expressionAsString: string, private _variableNames: List<any>) {}
 
@@ -240,6 +239,10 @@ class _ConvertAstIntoProtoRecords {
                            [key], null, obj);
   }
 
+  visitAssignment(ast: Assignment) { throw new BaseException('Not supported'); }
+
+  visitChain(ast: Chain) { throw new BaseException('Not supported'); }
+
   _visitAll(asts: List<any>) {
     var res = ListWrapper.createFixedSize(asts.length);
     for (var i = 0; i < asts.length; ++i) {
diff --git a/modules/angular2/src/facade/lang.dart b/modules/angular2/src/facade/lang.dart
index d94c0b4277..d811f0eeaf 100644
--- a/modules/angular2/src/facade/lang.dart
+++ b/modules/angular2/src/facade/lang.dart
@@ -88,6 +88,8 @@ class StringWrapper {
   static bool contains(String s, String substr) {
     return s.contains(substr);
   }
+
+  static bool isString(s) => s is String;
 }
 
 class StringJoiner {
diff --git a/modules/angular2/src/facade/lang.ts b/modules/angular2/src/facade/lang.ts
index 1b00b9ce09..2a97cd752c 100644
--- a/modules/angular2/src/facade/lang.ts
+++ b/modules/angular2/src/facade/lang.ts
@@ -132,6 +132,8 @@ export class StringWrapper {
   }
 
   static contains(s: string, substr: string): boolean { return s.indexOf(substr) != -1; }
+
+  static isString(s: any): boolean { return typeof s === 'string' || s instanceof String; }
 }
 
 export class StringJoiner {
diff --git a/modules/angular2/test/change_detection/parser/unparser.ts b/modules/angular2/test/change_detection/parser/unparser.ts
new file mode 100644
index 0000000000..96fab27906
--- /dev/null
+++ b/modules/angular2/test/change_detection/parser/unparser.ts
@@ -0,0 +1,180 @@
+import {
+  AST,
+  AstVisitor,
+  AccessMember,
+  Assignment,
+  Binary,
+  Chain,
+  Conditional,
+  Pipe,
+  FunctionCall,
+  ImplicitReceiver,
+  Interpolation,
+  KeyedAccess,
+  LiteralArray,
+  LiteralMap,
+  LiteralPrimitive,
+  MethodCall,
+  PrefixNot,
+  SafeAccessMember,
+  SafeMethodCall
+} from 'angular2/src/change_detection/parser/ast';
+
+
+import {StringWrapper, RegExpWrapper} from 'angular2/src/facade/lang';
+
+var quoteRegExp = RegExpWrapper.create('"');
+
+export class Unparser implements AstVisitor {
+  private _expression: string;
+
+  unparse(ast: AST) {
+    this._expression = '';
+    this._visit(ast);
+    return this._expression;
+  }
+
+  visitAccessMember(ast: AccessMember) {
+    this._visit(ast.receiver);
+
+    this._expression += ast.receiver instanceof ImplicitReceiver ? `${ast.name}` : `.${ast.name}`;
+  }
+
+  visitAssignment(ast: Assignment) {
+    this._visit(ast.target);
+    this._expression += ' = ';
+    this._visit(ast.value);
+  }
+
+  visitBinary(ast: Binary) {
+    this._visit(ast.left);
+    this._expression += ` ${ast.operation} `;
+    this._visit(ast.right);
+  }
+
+  visitChain(ast: Chain) {
+    ast.expressions.forEach(expression => {
+      this._visit(expression);
+      this._expression += ';'
+    });
+  }
+
+  visitConditional(ast: Conditional) {
+    this._visit(ast.condition);
+    this._expression += ' ? ';
+    this._visit(ast.trueExp);
+    this._expression += ' : ';
+    this._visit(ast.falseExp);
+  }
+
+  visitPipe(ast: Pipe) {
+    this._visit(ast.exp);
+    this._expression += ` | ${ast.name}`;
+    ast.args.forEach(arg => {
+      this._expression += ':';
+      this._visit(arg);
+    })
+  }
+
+  visitFunctionCall(ast: FunctionCall) {
+    this._visit(ast.target);
+    this._expression += '(';
+    var isFirst = true;
+    ast.args.forEach(arg => {
+      if (!isFirst) this._expression += ', ';
+      isFirst = false;
+      this._visit(arg);
+    });
+    this._expression += ')';
+  }
+
+  visitImplicitReceiver(ast: ImplicitReceiver) {}
+
+  visitInterpolation(ast: Interpolation) {
+    for (let i = 0; i < ast.strings.length; i++) {
+      this._expression += ast.strings[i];
+      if (i < ast.expressions.length) {
+        this._expression += '{{ ';
+        this._visit(ast.expressions[i]);
+        this._expression += ' }}';
+      }
+    }
+  }
+
+  visitKeyedAccess(ast: KeyedAccess) {
+    this._visit(ast.obj);
+    this._expression += '[';
+    this._visit(ast.key);
+    this._expression += ']';
+  }
+
+  visitLiteralArray(ast: LiteralArray) {
+    this._expression += '[';
+    var isFirst = true;
+    ast.expressions.forEach(expression => {
+      if (!isFirst) this._expression += ', ';
+      isFirst = false;
+      this._visit(expression);
+    });
+
+    this._expression += ']';
+  }
+
+  visitLiteralMap(ast: LiteralMap) {
+    this._expression += '{';
+    var isFirst = true;
+    for (let i = 0; i < ast.keys.length; i++) {
+      if (!isFirst) this._expression += ', ';
+      isFirst = false;
+      this._expression += `${ast.keys[i]}: `;
+      this._visit(ast.values[i]);
+    }
+
+    this._expression += '}';
+  }
+
+  visitLiteralPrimitive(ast: LiteralPrimitive) {
+    if (StringWrapper.isString(ast.value)) {
+      this._expression += `"${StringWrapper.replaceAll(ast.value, quoteRegExp, '\"')}"`;
+    } else {
+      this._expression += `${ast.value}`;
+    }
+  }
+
+  visitMethodCall(ast: MethodCall) {
+    this._visit(ast.receiver);
+    this._expression += ast.receiver instanceof ImplicitReceiver ? `${ast.name}(` :
+                                                                   `.${ast.name}(`;
+    var isFirst = true;
+    ast.args.forEach(arg => {
+      if (!isFirst) this._expression += ', ';
+      isFirst = false;
+      this._visit(arg);
+    });
+    this._expression += ')';
+  }
+
+  visitPrefixNot(ast: PrefixNot) {
+    this._expression += '!';
+    this._visit(ast.expression);
+  }
+
+  visitSafeAccessMember(ast: SafeAccessMember) {
+    this._visit(ast.receiver);
+    this._expression += `?.${ast.name}`;
+  }
+
+  visitSafeMethodCall(ast: SafeMethodCall) {
+    this._visit(ast.receiver);
+    this._expression += `?.${ast.name}(`;
+    var isFirst = true;
+    ast.args.forEach(arg => {
+      if (!isFirst) this._expression += ', ';
+      isFirst = false;
+      this._visit(arg);
+    });
+    this._expression += ')';
+  }
+
+  private _visit(ast: AST) { ast.visit(this); }
+}
diff --git a/modules/angular2/test/change_detection/parser/unparser_spec.ts b/modules/angular2/test/change_detection/parser/unparser_spec.ts
new file mode 100644
index 0000000000..7ff995364a
--- /dev/null
+++ b/modules/angular2/test/change_detection/parser/unparser_spec.ts
@@ -0,0 +1,112 @@
+import {ddescribe, describe, it, xit, iit, expect, beforeEach} from 'angular2/test_lib';
+
+import {
+  AST,
+  ASTWithSource,
+  AccessMember,
+  Assignment,
+  Binary,
+  Chain,
+  Conditional,
+  Pipe,
+  ImplicitReceiver,
+  Interpolation,
+  KeyedAccess,
+  LiteralArray,
+  LiteralMap,
+  LiteralPrimitive,
+  MethodCall,
+  PrefixNot,
+  SafeAccessMember,
+  SafeMethodCall
+} from 'angular2/src/change_detection/parser/ast';
+
+import {Parser} from 'angular2/src/change_detection/parser/parser';
+import {Lexer} from 'angular2/src/change_detection/parser/lexer';
+import {Unparser} from './unparser';
+
+import {reflector} from 'angular2/src/reflection/reflection';
+
+import {isPresent, Type} from 'angular2/src/facade/lang';
+
+export function main() {
+  let parser: Parser = new Parser(new Lexer(), reflector);
+  let unparser: Unparser = new Unparser();
+
+  function parseAction(text, location = null): ASTWithSource {
+    return parser.parseAction(text, location);
+  }
+
+  function parseBinding(text, location = null): ASTWithSource {
+    return parser.parseBinding(text, location);
+  }
+
+  function check(expression: string, type: Type): void {
+    var ast = parseAction(expression).ast;
+    if (isPresent(type)) {
+      expect(ast).toBeAnInstanceOf(type);
+    }
+    expect(unparser.unparse(ast)).toEqual(expression);
+  }
+
+  describe('Unparser', () => {
+    it('should support AccessMember', () => {
+      check('a', AccessMember);
+      check('a.b', AccessMember);
+    });
+
+    it('should support Assignment', () => { check('a = b', Assignment); });
+
+    it('should support Binary', () => { check('a && b', Binary); });
+
+    it('should support Chain', () => { check('a;b;', Chain); });
+
+    it('should support Conditional', () => { check('a ? b : c', Conditional); });
+
+    it('should support Pipe', () => {
+      var originalExp = 'a | b';
+      var ast = parseBinding(originalExp).ast;
+      expect(ast).toBeAnInstanceOf(Pipe);
+      expect(unparser.unparse(ast)).toEqual(originalExp);
+    });
+
+    it('should support KeyedAccess', () => { check('a[b]', KeyedAccess); });
+
+    it('should support LiteralArray', () => { check('[a, b]', LiteralArray); });
+
+    it('should support LiteralMap', () => { check('{a: b, c: d}', LiteralMap); });
+
+    it('should support LiteralPrimitive', () => {
+      check('true', LiteralPrimitive);
+      check('"a"', LiteralPrimitive);
+      check('1.234', LiteralPrimitive);
+    });
+
+    it('should support MethodCall', () => {
+      check('a(b, c)', MethodCall);
+      check('a.b(c, d)', MethodCall);
+    });
+
+    it('should support PrefixNot', () => { check('!a', PrefixNot); });
+
+    it('should support SafeAccessMember', () => { check('a?.b', SafeAccessMember); });
+
+    it('should support SafeMethodCall', () => { check('a?.b(c, d)', SafeMethodCall); });
+
+    it('should support complex expression', () => {
+      var originalExp = 'a + 3 * fn([c + d | e.f], {a: 3})[g].h && i';
+      var ast = parseBinding(originalExp).ast;
+      expect(unparser.unparse(ast)).toEqual(originalExp);
+    });
+
+    it('should support Interpolation', () => {
+      var ast = parser.parseInterpolation('a {{ b }}', null).ast;
+      expect(ast).toBeAnInstanceOf(Interpolation);
+      expect(unparser.unparse(ast)).toEqual('a {{ b }}');
+
+      ast = parser.parseInterpolation('a {{ b }} c', null).ast;
+      expect(ast).toBeAnInstanceOf(Interpolation);
+      expect(unparser.unparse(ast)).toEqual('a {{ b }} c');
+    });
+  });
+}