crocks/helpers/pipeK.js

A collection of well known Algebraic Datatypes for your utter enjoyment.

/** @license ISC License (c) copyright 2017 original and current authors */
/** @author Ian Hofmann-Hicks (evil) */

var isChain = require('../core/isChain')
var isFunction = require('../core/isFunction')

var err = 'pipeK: Chain returning functions of the same type required'

function pipeK(head) {
  var fns = [], len = arguments.length - 1;
  while ( len-- > 0 ) fns[ len ] = arguments[ len + 1 ];

  if(!(arguments.length && isFunction(head))) {
    throw new TypeError(err)
  }

  if(arguments.length === 1) {
    return head
  }

  var tail = fns.reduce(function (comp, fn) {
    if(!isFunction(fn)) {
      throw new TypeError(err)
    }

    return function(m) {
      if(!isChain(m)) {
        throw new TypeError(err)
      }
      return comp(m).chain(fn)
    }
  }, function (x) { return x; })

  return function() {
    return tail(head.apply(null, arguments))
  }
}

module.exports = pipeK