函数柯理化

简单版.js

function curry(fn) {
  var args = []
  var len = fn.length
  
  var result = function(n) {
    args.push(n)
    len--
    if (len > 0) {
      return result
    } else {
      fn.apply(null, args)
    }
  }
  
  return result
}