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Author: basarat

GLOSSARY.md

@@ -0,0 +1,2 @@
+# Duck Typing
+If it walks like a duck and quacks like a duck, its a duck. For TypeScript if it has all the members structurally then it okay for other things (irrespecitive of name) that accept that structure.

code/testing.js

@@ -0,0 +1,16 @@
+var point2D = {
+    x: 0,
+    y: 10,
+};
+var point3D = {
+    x: 0,
+    y: 10,
+    z: 20
+};
+function iTakePoint2D(point) {
+}
+iTakePoint2D(point2D);
+iTakePoint2D(point3D);
+iTakePoint2D({
+    x: 0
+});

code/testing.ts

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+interface Point2D {
+    x: number;
+    y: number;
+}
+interface Point3D {
+    x: number;
+    y: number;
+    z: number;
+}
+var point2D: Point2D = { x: 0, y: 10, }
+var point3D: Point3D = { x: 0, y: 10, z: 20 }
+function iTakePoint2D(point: Point2D) { /* do something */ }
+
+iTakePoint2D(point2D); // exact match okay
+iTakePoint2D(point3D); // extra information okay
+iTakePoint2D({ x: 0 }); // Error: missing information `y`

code/tsconfig.json

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+{
+    "version": "1.4.1",
+    "compilerOptions": {
+        "target": "es5",
+        "module": "commonjs",
+        "declaration": false,
+        "noImplicitAny": false,
+        "removeComments": true,
+        "noLib": false
+    },
+    "filesGlob": [
+        "./**/*.ts",
+        "!./node_modules/**/*.ts"
+    ],
+    "files": [
+        "./testing.ts"
+    ]
+}

docs/why-typescript.md

@@ -47,13 +47,22 @@ We will discuss all the details of all the annotation methods supported by TypeS
 In some languages (specifically nominally typed ones) static typing results in unnecessary ceremony because even though *you know* that the code will work fine the language semantics force you to copy stuff around. This is why stuff like [automapper for C#](http://automapper.org/) exists. In TypeScript because we really want it to be easy for JavaScript developers, and be minimum cognitive overload types are *structural*. This means that *duck typing* is a first class language construct. An example is in order:
 
 ```ts
-interface Foo{
-    name: string;
+interface Point2D {
+    x: number;
+    y: number;
 }
-interfaace Bar{
-    name: string;
-    class: number;
+interface Point3D {
+    x: number;
+    y: number;
+    z: number;
 }
+var point2D: Point2D = { x: 0, y: 10, }
+var point3D: Point3D = { x: 0, y: 10, z: 20 }
+function iTakePoint2D(point: Point2D) { /* do something */ }
+
+iTakePoint2D(point2D); // exact match okay
+iTakePoint2D(point3D); // extra information okay
+iTakePoint2D({ x: 0 }); // Error: missing information `y`
 ```