builtins.js

var x = Math.PI; //: number
Math.cos(x); //: number

var a = [1, 2, 3]; //: [number]
a.slice(2); //: [number]
a.pop(); //: number

["x"].concat(["hi"]); //: [string]

[true, false, true].filter(function(x){return x;}); //: [bool]

[].map(function() {return "x";}); //: [string]

[].reduce(function(a, b) { return a - 2; }, 0); //: number

Math.cos.call(null, 10); //: number

(10).toFixed; //: fn(digits: number) -> string

"foo bar baz".split(" "); //: [string]

toString; //: fn() -> string

new Date; //: Date

var num = new Number(1);
num; //: Number

"foo".toString(); //: string

Array.prototype.slice.call([1, 2, 3], 1); //: [number]

Array.prototype.slice.apply([1, 2, 3], [1]); //: [number]

String.prototype.indexOf.bind("abcde", "a"); //: fn(from?: number) -> number