柯里化学习

把函数变为接收一个参数,返回一个值得固定形式.

f(x,y,z) -> f(x)(y)(z)

特性

1 匿名函数
2 每个函数只有一个输入参数

function currying(fn) {
   var args = [].slice.call(arguments, 1);
   return function() {
        var newArgs = args.concat([].slice.call(arguments));
        return fn.apply(null, newArgs);
   }
}

var add = function(x,y) {
  return x + y;
}

var result = curry(add, 5);

console.log(result(10));

function curryRight(fn) {
    var args = [].slice.call(arguments, arguments.length -1 );
    return function() {
        var newArgs = [].concat([].slice.call(arguments), args);
        return fn.apply(null, newArgs);
    }
}

function curry(fn, length) {
    // capture fn's # of parameters
    length = length || fn.length;
    return function () {
        if (arguments.length < length) {
            // not all arguments have been specified. Curry once more.
            var combined = [fn].concat(toArray(arguments));
            return length - arguments.length > 0
                ? curry(sub_curry.apply(this, combined), length - arguments.length)
                : sub_curry.call(this, combined );
        } else {
            // all arguments have been specified, actually call function
            return fn.apply(this, arguments);
        }
    };
}

var fn = curry(function(a, b, c) { return [a, b, c]; });

// these are all equivalent
fn("a", "b", "c");
fn("a", "b", "c");
fn("a", "b")("c");
fn("a")("b", "c");
fn("a")("b")("c");
//=> ["a", "b", "c"]