JavaScript-Curry

Currying allows you to easily create custom functions by partially invoking an existing function. Here’s a simple example:

var add = function(a,b) {
    return a + b;
}

var addTen = add.curry(10); //create function that returns 10 + argument
addTen(20); //30

Generally, curry returns a copy of the invoking function, with its first n arguments pre-assigned with the arguments passed by the curry invocation.

The curry function does not exist in native JavaScript, but it’s easy to write your own. Here I’m augmenting function’s prototype with an implementation based on the Prototype framework. (Notice I’m also throwing in a toArray function for convenience. This is because function’s arguments property is not a true array, and we need it to work with array’s concat function)

function toArray(enum) {
    return Array.prototype.slice.call(enum);
}

Function.prototype.curry = function() {
    if (arguments.length<1) {
        return this; //nothing to curry with - return function
    }
    var __method = this;
    var args = toArray(arguments);
    return function() {
        return __method.apply(this, args.concat(toArray(arguments)));
    }
}

 

The returned function expects to be invoked with additional argument(s) which it will concatenate with the argument(s) it got from the curry function.

A CURRY FUNCTION IN JAVASCRIPT

function curry (fn, scope) {

    var scope = scope || window;

    var args = [];

    for (var i=2, len = arguments.length; i < len; ++i) {

        args.push(arguments[i]);

    };

    return function() {

        fn.apply(scope, args);

    };

}

 

Quote From:

Curry: cooking up tastier functions

JavaScript currying