diff --git a/src/ast.ts b/src/ast.ts
index 4a363664..65210b8b 100644
--- a/src/ast.ts
+++ b/src/ast.ts
@@ -351,6 +351,31 @@ export abstract class Node {
     if (stmt.arguments = args)
       for (var i: i32 = 0, k: i32 = (<Expression[]>args).length; i < k; ++i)
         (<Expression[]>args)[i].parent = stmt;
+    if (expression.kind == NodeKind.IDENTIFIER) {
+      switch ((<IdentifierExpression>expression).name) {
+
+        case "global":
+          stmt.decoratorKind = DecoratorKind.GLOBAL;
+          break;
+
+        case "operator":
+          stmt.decoratorKind = DecoratorKind.OPERATOR;
+          break;
+
+        case "struct":
+          stmt.decoratorKind = DecoratorKind.STRUCT;
+          break;
+
+        case "size":
+          stmt.decoratorKind = DecoratorKind.SIZE;
+          break;
+
+        default:
+          stmt.decoratorKind = DecoratorKind.CUSTOM;
+          break;
+      }
+    } else
+      stmt.decoratorKind = DecoratorKind.CUSTOM;
     return stmt;
   }
 
@@ -1333,6 +1358,15 @@ export class ContinueStatement extends Statement {
   }
 }
 
+/** Built-in decorator kinds. */
+export const enum DecoratorKind {
+  CUSTOM,
+  GLOBAL,
+  OPERATOR,
+  STRUCT,
+  SIZE
+}
+
 /** Depresents a decorator. */
 export class Decorator extends Statement {
 
@@ -1342,6 +1376,8 @@ export class Decorator extends Statement {
   name: Expression;
   /** Argument expressions. */
   arguments: Expression[] | null;
+  /** Built-in kind, if applicable. */
+  decoratorKind: DecoratorKind;
 
   serialize(sb: string[]): void {
     sb.push("@");
@@ -2153,7 +2189,7 @@ export function hasModifier(kind: ModifierKind, modifiers: Modifier[] | null): b
 }
 
 /** Gets a specific decorator within the specified decorators, if present. */
-export function getDecorator(name: string, decorators: Decorator[] | null): Decorator | null {
+export function getFirstDecorator(name: string, decorators: Decorator[] | null): Decorator | null {
   if (decorators)
     for (var i = 0, k = decorators.length; i < k; ++i) {
       var decorator = decorators[i];
@@ -2166,7 +2202,7 @@ export function getDecorator(name: string, decorators: Decorator[] | null): Deco
 
 /** Tests if a specific decorator is present within the specified decorators. */
 export function hasDecorator(name: string, decorators: Decorator[] | null): bool {
-  return getDecorator(name, decorators) != null;
+  return getFirstDecorator(name, decorators) != null;
 }
 
 /** Serializes the specified node to its TypeScript representation. */
diff --git a/src/program.ts b/src/program.ts
index d0de37e2..d9883ae7 100644
--- a/src/program.ts
+++ b/src/program.ts
@@ -38,11 +38,17 @@ import {
   TypeNode,
   TypeParameter,
   Decorator,
+  DecoratorKind,
 
   Expression,
+  ElementAccessExpression,
   IdentifierExpression,
+  LiteralExpression,
+  LiteralKind,
   PropertyAccessExpression,
   StringLiteralExpression,
+  SuperExpression,
+  ThisExpression,
   CallExpression,
   NewExpression,
 
@@ -68,9 +74,7 @@ import {
   hasDecorator,
   hasModifier,
   mangleInternalName,
-  ElementAccessExpression,
-  ThisExpression,
-  SuperExpression
+  getFirstDecorator
 } from "./ast";
 
 import {
@@ -354,6 +358,7 @@ export class Program extends DiagnosticEmitter {
   private initializeMethod(declaration: MethodDeclaration, classPrototype: ClassPrototype): void {
     var name = declaration.name.name;
     var internalName = declaration.internalName;
+    var instancePrototype: FunctionPrototype | null = null;
 
     // static methods become global functions
     if (hasModifier(ModifierKind.STATIC, declaration.modifiers)) {
@@ -382,12 +387,56 @@ export class Program extends DiagnosticEmitter {
         }
       } else
         classPrototype.instanceMembers = new Map();
-      var instancePrototype = new FunctionPrototype(this, name, internalName, declaration, classPrototype);
+      instancePrototype = new FunctionPrototype(this, name, internalName, declaration, classPrototype);
       // if (classPrototype.isStruct && instancePrototype.isAbstract) {
       //   this.error( Structs cannot declare abstract methods. );
       // }
       classPrototype.instanceMembers.set(name, instancePrototype);
     }
+
+    // handle operator annotations. operators are instance methods taking a second argument of the
+    // instance's type. return values vary depending on the operation.
+    if (declaration.decorators) {
+      for (var i = 0, k = declaration.decorators.length; i < k; ++i) {
+        var decorator = declaration.decorators[i];
+        if (decorator.decoratorKind == DecoratorKind.OPERATOR) {
+          if (!instancePrototype) {
+            this.error(DiagnosticCode.Operation_not_supported, decorator.range);
+            continue;
+          }
+          var numArgs = decorator.arguments && decorator.arguments.length || 0;
+          if (numArgs == 1) {
+            var firstArg = (<Expression[]>decorator.arguments)[0];
+            if (firstArg.kind == NodeKind.LITERAL && (<LiteralExpression>firstArg).literalKind == LiteralKind.STRING) {
+              switch ((<StringLiteralExpression>firstArg).value) {
+
+                case "[]":
+                  classPrototype.opIndexedGet = instancePrototype;
+                  break;
+
+                case "[]=":
+                  classPrototype.opIndexedSet = instancePrototype;
+                  break;
+
+                case "+":
+                  classPrototype.opConcat = instancePrototype;
+                  break;
+
+                case "==":
+                  classPrototype.opEquals = instancePrototype;
+                  break;
+
+                default: // TBD: does it make sense to provide more, even though not JS/TS-compatible?
+                  this.error(DiagnosticCode.Operation_not_supported, firstArg.range);
+              }
+            } else
+              this.error(DiagnosticCode.String_literal_expected, firstArg.range);
+          } else
+            this.error(DiagnosticCode.Expected_0_arguments_but_got_1, decorator.range, "1", numArgs.toString(0));
+        } else if (decorator.decoratorKind != DecoratorKind.CUSTOM) // methods support @operator only
+          this.error(DiagnosticCode.Operation_not_supported, decorator.range);
+      }
+    }
   }
 
   private initializeAccessor(declaration: MethodDeclaration, classPrototype: ClassPrototype, isGetter: bool): void {
@@ -1449,6 +1498,7 @@ export class FunctionPrototype extends Element {
     }
 
     // resolve parameters
+    // TODO: 'this' type
     k = declaration.parameters.length;
     var parameters = new Array<Parameter>(k);
     var parameterTypes = new Array<Type>(k);
@@ -1466,6 +1516,7 @@ export class FunctionPrototype extends Element {
     }
 
     // resolve return type
+    // TODO: 'this' type
     var returnType: Type;
     if (this.isSetter) {
       returnType = Type.void; // not annotated
@@ -1770,6 +1821,15 @@ export class ClassPrototype extends Element {
   /** Instance member prototypes. */
   instanceMembers: Map<string,Element> | null = null;
 
+  /** Overloaded indexed get method, if any. */
+  opIndexedGet: FunctionPrototype | null;
+  /** Overloaded indexed set method, if any. */
+  opIndexedSet: FunctionPrototype | null;
+  /** Overloaded concatenation method, if any. */
+  opConcat: FunctionPrototype | null;
+  /** Overloaded equality comparison method, if any. */
+  opEquals: FunctionPrototype | null;
+
   constructor(program: Program, simpleName: string, internalName: string, declaration: ClassDeclaration | null = null) {
     super(program, simpleName, internalName);
     if (this.declaration = declaration) {
diff --git a/std/assembly/array.ts b/std/assembly/array.ts
index a9e010af..67c90aa4 100644
--- a/std/assembly/array.ts
+++ b/std/assembly/array.ts
@@ -18,13 +18,13 @@ export class Array<T> {
   }
 
   @operator("[]")
-  get(index: i32): T {
+  private __get(index: i32): T {
     assert(index > 0 && index < this.capacity);
     throw new Error("not implemented");
   }
 
   @operator("[]=")
-  set(index: i32, value: T): void {
+  private __set(index: i32, value: T): void {
     assert(index > 0 && index < this.capacity);
     throw new Error("not implemented");
   }
@@ -46,12 +46,12 @@ export class CArray<T> {
   private constructor() {}
 
   @operator("[]")
-  get(index: usize): T {
+  private __get(index: usize): T {
     return load<T>(changetype<usize>(this) + index * sizeof<T>());
   }
 
   @operator("[]=")
-  set(index: usize, value: T): void {
+  private __set(index: usize, value: T): void {
     store<T>(changetype<usize>(this) + index * sizeof<T>(), value);
   }
 }
diff --git a/std/assembly/string.ts b/std/assembly/string.ts
index 8c03211f..38521c43 100644
--- a/std/assembly/string.ts
+++ b/std/assembly/string.ts
@@ -13,6 +13,7 @@ export class String {
     this.length = lenght;
   }
 
+  @operator("[]")
   charAt(pos: i32): String {
     assert(this != null);
     return pos < 0 || pos >= this.length ? EMPTY
@@ -39,7 +40,7 @@ export class String {
   }
 
   @operator("+")
-  concat(other: String): String {
+  concat(other: this): String {
     assert(this != null);
     assert(other != null);
     var thisLen: isize = this.length;
@@ -59,7 +60,7 @@ export class String {
     );
   }
 
-  endsWith(searchString: String, endPosition: i32 = 0x7fffffff): bool {
+  endsWith(searchString: this, endPosition: i32 = 0x7fffffff): bool {
     assert(this != null);
     assert(searchString != null);
     var end: isize = <isize>min<i32>(max<i32>(endPosition, 0), this.length);
@@ -71,18 +72,18 @@ export class String {
   }
 
   @operator("==")
-  equals(other: String): bool {
+  private __eq(other: this): bool {
     assert(this != null);
     assert(other != null);
     return this.length != other.length ? false
          : !Heap.compare(this.ptr, other.ptr, <usize>this.length);
   }
 
-  includes(searchString: String, position: i32 = 0): bool {
+  includes(searchString: this, position: i32 = 0): bool {
     return this.indexOf(searchString, position) != -1;
   }
 
-  indexOf(searchString: String, position: i32 = 0): i32 {
+  indexOf(searchString: this, position: i32 = 0): i32 {
     assert(this != null);
     assert(searchString != null);
     var pos: isize = position;
@@ -95,7 +96,7 @@ export class String {
     return -1;
   }
 
-  startsWith(searchString: String, position: i32 = 0): bool {
+  startsWith(searchString: this, position: i32 = 0): bool {
     assert(this != null);
     assert(searchString != null);
     var pos: isize = position;
diff --git a/tests/compiler/showcase.optimized-inlined.wast b/tests/compiler/showcase.optimized-inlined.wast
index 2cabb817..4c56074e 100644
--- a/tests/compiler/showcase.optimized-inlined.wast
+++ b/tests/compiler/showcase.optimized-inlined.wast
@@ -34,8 +34,8 @@
  (global $showcase/AnEnum.TWO i32 (i32.const 2))
  (global $showcase/AnEnum.FOUR i32 (i32.const 4))
  (global $showcase/AnEnum.FIVE i32 (i32.const 5))
- (global $showcase/AnEnum.FOURTYTWO (mut i32) (i32.const 0))
- (global $showcase/AnEnum.FOURTYTHREE (mut i32) (i32.const 0))
+ (global $showcase/AnEnum.FORTYTWO (mut i32) (i32.const 0))
+ (global $showcase/AnEnum.FORTYTHREE (mut i32) (i32.const 0))
  (global $memcpy/dest (mut i32) (i32.const 0))
  (global $showcase/aClassInstance (mut i32) (i32.const 8))
  (global $showcase/AClass.aStaticField (mut i32) (i32.const 0))
@@ -3944,25 +3944,25 @@
    )
    (unreachable)
   )
-  (set_global $showcase/AnEnum.FOURTYTWO
+  (set_global $showcase/AnEnum.FORTYTWO
    (get_global $showcase/aMutableGlobal)
   )
-  (set_global $showcase/AnEnum.FOURTYTHREE
+  (set_global $showcase/AnEnum.FORTYTHREE
    (i32.add
-    (get_global $showcase/AnEnum.FOURTYTWO)
+    (get_global $showcase/AnEnum.FORTYTWO)
     (i32.const 1)
    )
   )
   (if
    (i32.ne
-    (get_global $showcase/AnEnum.FOURTYTWO)
+    (get_global $showcase/AnEnum.FORTYTWO)
     (i32.const 42)
    )
    (unreachable)
   )
   (if
    (i32.ne
-    (get_global $showcase/AnEnum.FOURTYTHREE)
+    (get_global $showcase/AnEnum.FORTYTHREE)
     (i32.const 43)
    )
    (unreachable)
diff --git a/tests/compiler/showcase.optimized.wast b/tests/compiler/showcase.optimized.wast
index 26b8e789..d14eddf4 100644
--- a/tests/compiler/showcase.optimized.wast
+++ b/tests/compiler/showcase.optimized.wast
@@ -34,8 +34,8 @@
  (global $showcase/AnEnum.TWO i32 (i32.const 2))
  (global $showcase/AnEnum.FOUR i32 (i32.const 4))
  (global $showcase/AnEnum.FIVE i32 (i32.const 5))
- (global $showcase/AnEnum.FOURTYTWO (mut i32) (i32.const 0))
- (global $showcase/AnEnum.FOURTYTHREE (mut i32) (i32.const 0))
+ (global $showcase/AnEnum.FORTYTWO (mut i32) (i32.const 0))
+ (global $showcase/AnEnum.FORTYTHREE (mut i32) (i32.const 0))
  (global $memcpy/dest (mut i32) (i32.const 0))
  (global $showcase/aClassInstance (mut i32) (i32.const 8))
  (global $showcase/AClass.aStaticField (mut i32) (i32.const 0))
@@ -3961,25 +3961,25 @@
    )
    (unreachable)
   )
-  (set_global $showcase/AnEnum.FOURTYTWO
+  (set_global $showcase/AnEnum.FORTYTWO
    (get_global $showcase/aMutableGlobal)
   )
-  (set_global $showcase/AnEnum.FOURTYTHREE
+  (set_global $showcase/AnEnum.FORTYTHREE
    (i32.add
-    (get_global $showcase/AnEnum.FOURTYTWO)
+    (get_global $showcase/AnEnum.FORTYTWO)
     (i32.const 1)
    )
   )
   (if
    (i32.ne
-    (get_global $showcase/AnEnum.FOURTYTWO)
+    (get_global $showcase/AnEnum.FORTYTWO)
     (i32.const 42)
    )
    (unreachable)
   )
   (if
    (i32.ne
-    (get_global $showcase/AnEnum.FOURTYTHREE)
+    (get_global $showcase/AnEnum.FORTYTHREE)
     (i32.const 43)
    )
    (unreachable)
diff --git a/tests/compiler/showcase.ts b/tests/compiler/showcase.ts
index f2101231..24830180 100644
--- a/tests/compiler/showcase.ts
+++ b/tests/compiler/showcase.ts
@@ -48,15 +48,15 @@ export enum AnEnum {
                               // or be omitted
   FOUR = AnEnum.TWO + 2,      // or reference other values (and remain constant through precomputation)
   FIVE,                       // and continue from there
-  FOURTYTWO = aMutableGlobal, // or reference mutable values but then can't be exported
-  FOURTYTHREE                 // and even continue from there without being exported (tsc doesn't allow this)
+  FORTYTWO = aMutableGlobal,  // or reference mutable values but then can't be exported
+  FORTYTHREE                  // and even continue from there without being exported (tsc doesn't allow this)
 }
 assert(AnEnum.ONE == 1);
 assert(AnEnum.TWO == 2);
 assert(AnEnum.FOUR == 4);
 assert(AnEnum.FIVE == 5);
-assert(AnEnum.FOURTYTWO == 42);
-assert(AnEnum.FOURTYTHREE == 43);
+assert(AnEnum.FORTYTWO == 42);
+assert(AnEnum.FORTYTHREE == 43);
 
 // In fact, there are a couple of things asc just waves through where tsc refuses to
 1, 2, 3;                      // for example not-so-useful comma expressions
@@ -94,13 +94,13 @@ class AClass {
   aField: i32;
 }
 class ADerivedClass extends AClass {
-  aNotherField: f32;
-  get aWildAccessorAppears(): f32 { return this.aNotherField; }
-  set aWildAccessorAppears(val: f32) { this.aNotherField = val; }
+  anotherField: f32;
+  get aWildAccessorAppears(): f32 { return this.anotherField; }
+  set aWildAccessorAppears(val: f32) { this.anotherField = val; }
 }
 var aClassInstance = changetype<ADerivedClass>(<usize>8);
 aClassInstance.aField = 42;
-aClassInstance.aNotherField = 9000;
+aClassInstance.anotherField = 9000;
 assert(load<i32>(8) == 42);
 assert(load<f32>(12) == 9000);
 
diff --git a/tests/compiler/showcase.wast b/tests/compiler/showcase.wast
index 9ed8bc83..904d26b3 100644
--- a/tests/compiler/showcase.wast
+++ b/tests/compiler/showcase.wast
@@ -67,8 +67,8 @@
  (global $showcase/AnEnum.TWO i32 (i32.const 2))
  (global $showcase/AnEnum.FOUR i32 (i32.const 4))
  (global $showcase/AnEnum.FIVE i32 (i32.const 5))
- (global $showcase/AnEnum.FOURTYTWO (mut i32) (i32.const 0))
- (global $showcase/AnEnum.FOURTYTHREE (mut i32) (i32.const 0))
+ (global $showcase/AnEnum.FORTYTWO (mut i32) (i32.const 0))
+ (global $showcase/AnEnum.FORTYTHREE (mut i32) (i32.const 0))
  (global $memcpy/base i32 (i32.const 8))
  (global $memcpy/dest (mut i32) (i32.const 0))
  (global $showcase/aClassInstance (mut i32) (i32.const 8))
@@ -5802,12 +5802,12 @@
    )
    (unreachable)
   )
-  (set_global $showcase/AnEnum.FOURTYTWO
+  (set_global $showcase/AnEnum.FORTYTWO
    (get_global $showcase/aMutableGlobal)
   )
-  (set_global $showcase/AnEnum.FOURTYTHREE
+  (set_global $showcase/AnEnum.FORTYTHREE
    (i32.add
-    (get_global $showcase/AnEnum.FOURTYTWO)
+    (get_global $showcase/AnEnum.FORTYTWO)
     (i32.const 1)
    )
   )
@@ -5850,7 +5850,7 @@
   (if
    (i32.eqz
     (i32.eq
-     (get_global $showcase/AnEnum.FOURTYTWO)
+     (get_global $showcase/AnEnum.FORTYTWO)
      (i32.const 42)
     )
    )
@@ -5859,7 +5859,7 @@
   (if
    (i32.eqz
     (i32.eq
-     (get_global $showcase/AnEnum.FOURTYTHREE)
+     (get_global $showcase/AnEnum.FORTYTHREE)
      (i32.const 43)
     )
    )