1. /**
    2.  编程题:函数柯里化
    3.  function curry(func) {
    4.   // something
    6. }
    7.  function sum(a, b, c) {
    8.   return a + b + c;
    9. }
    11.  let curriedSum = curry(sum);
    14.  console.log(curriedSum(1, 2, 3)); // 6, still callable normally
    15.  console.log(curriedSum(1)(2, 3)); // 6, currying of 1st arg
    16.  console.log(curriedSum(1)(2)(3)); // 6, full currying
    18.  */
    21. function curry(func) {
    22.   return  function fn(...agrs) {
    23.     if (agrs.length >= func.length) {
    24.       return func.apply(this, agrs)
    25.     } else {
    26.       return function (...args2) {
    27.         return fn.apply(this, agrs.concat(args2))
    28.       }
    29.     }
    30.   }
    31. }
    33. function sum(a, b, c) {
    34.   return a + b + c;
    35. }
    37. let curriedSum = curry(sum);
    40. console.log(curriedSum(1, 2, 3)); // 6, still callable normally
    41. console.log(curriedSum(1)(2, 3)); // 6, currying of 1st arg
    42. console.log(curriedSum(1)(2)(3)); // 6, full currying