JavaScript Curry

 感觉就是C++中的 functor+bind.

http://stackoverflow.com/questions/5176313/javascript-curry

// define the curry() function

function curry(fn, scope) {

    // set the scope to window (the default global object) if no scope was passed in.
    scope = scope || window;

    // Convert arguments into a plain array, because it is sadly not one.
    // args will have all extra arguments in it, not including the first 2 (fn, scope)
    // The loop skips fn and scope by starting at the index 2 with i = 2
    var args = [];
    for (var i = 2, len = arguments.length; i < len; ++i) {
        args.push(arguments[i]);
    }

    // Create the new function to return
    return function() {

        // Convert any arguments passed to the this function into an array.
        // This time we want them all
        var args2 = [];
        for (var i = 0; i < arguments.length; i++) {
            args.push(arguments[i]);
        }

        // Here we combine any args originally passed to curry, with the args
        // passed directly to this function.
        //   curry(fn, scope, a, b)(c, d)
        // would set argstotal = [a, b, c, d]
        var argstotal = args.concat(args2);

        // execute the original function being curried in the context of "scope"
        // but with our combined array of arguments
        return fn.apply(scope, argstotal);
    };
}

// Create a function to be curried

function diffPoint(x1, y1, x2, y2) {
    return [Math.abs(x2 - x1), Math.abs(y2 - y1)];
}

// Create a curried version of the diffPoint() function
//   arg1: the function to curry
//   arg2: the scope (passing a falsy value causes the curry function to use window instead)
//   arg3: first argument of diffPoint() to bake in (x1)
//   arg4: second argument of diffPoint() to bake in (y1)
var diffOrigin = curry(diffPoint, null, 3.0, 4.0);

// Call the curried function
// Since the first 2 args where already filled in with the curry, we supply x2 and y2 only
var newPt = diffOrigin(6.42, 8.0);