Simple Maybe implementation

gistfile1.js

(function(window) {
    function Some(v) {
  	this.value = v;
    }

    Some.prototype = {
	map: function(f) {
	    return some(f(this.value));
	},
	isNone: false,
	fromMaybe: function() {
	    return this.value;
	},
	fromSome: function() {
	    return this.value;
	}
    }

    function None() {}

    None.prototype = {
	map: function() {
	    return none;
	},
	isNone: true,
	fromMaybe: function(x) {
	    return x;
	},
	fromSome: function() {
	    throw new Error('It is not nothing');
	}
    }

    var none = window.none = new None();
    var some = window.some = function(x) { return new Some(x) };
})(this);