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/** 冴羽-专题系列目录-JavaScript专题之函数柯里化
function sub_curry(fn) {
    var args = [].slice.call(arguments, 1);
    return function() {
        return fn.apply(this, args.concat([].slice.call(arguments)));
    };
}

function curry(fn, length) {

    length = length || fn.length;

    var slice = Array.prototype.slice;

    return function() {
        if (arguments.length < length) {
            var combined = [fn].concat(slice.call(arguments));
            return curry(sub_curry.apply(this, combined), length - arguments.length);
        } else {
            return fn.apply(this, arguments);
        }
    };
}
*/


function curry(fun, ...rest) {
  let argsLength = fun.length
  return function(...args) {
    let allArgs = rest.concat(args)
    if (allArgs.length >= argsLength) {
      return fun.apply(this, allArgs)
    } else {
      return curry.apply(this, [fun].concat(allArgs))
    }
  }
}

let testFun = function(a, b, c, d) {
  return [a, b, c, d]
}

let curryTestFun = curry(testFun)
// console.log(curryTestFun(1, 2, 3, 4))
// console.log(curryTestFun(1)(2)(3)(4))
// console.log(curryTestFun(1)(3, 2)(3))
let curryTestFun1 = curryTestFun(3)
console.log(curryTestFun1(2, 3, 4))
console.log(curryTestFun1(3)(6, 4))
let curryTestFun2 = curry(testFun, 10)
console.log(curryTestFun2(3)(6, 4))