From d32196ff3640f487c69fffc9e4e8f04e93524cb4 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Tue, 15 Nov 2016 12:14:46 -0800
Subject: [PATCH] Add predefined mapped types and revise Object.freeze

---
 src/lib/es5.d.ts | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
index 2c457a432c6..e402a96fade 100644
--- a/src/lib/es5.d.ts
+++ b/src/lib/es5.d.ts
@@ -180,7 +180,7 @@ interface ObjectConstructor {
       * Prevents the modification of existing property attributes and values, and prevents the addition of new properties.
       * @param o Object on which to lock the attributes.
       */
-    freeze<T>(o: T): T;
+    freeze<T>(o: T): Readonly<T>;
 
     /**
       * Prevents the addition of new properties to an object.
@@ -1343,6 +1343,34 @@ interface ArrayLike<T> {
     readonly [n: number]: T;
 }
 
+/**
+ * Make all properties in T optional
+ */
+type Partial<T> = {
+    [P in keyof T]?: T[P];
+};
+
+/**
+ * Make all properties in T readonly
+ */
+type Readonly<T> = {
+    readonly [P in keyof T]: T[P];
+};
+
+/**
+ * From T pick a set of properties K
+ */
+type Pick<T, K extends keyof T> = {
+    [P in K]: T[P];
+}
+
+/**
+ * Construct a type with a set of properties K of type T
+ */
+type Record<K extends string | number, T> = {
+    [P in K]: T;
+}
+
 /**
   * Represents a raw buffer of binary data, which is used to store data for the
   * different typed arrays. ArrayBuffers cannot be read from or written to directly,