crocks/Maybe/getProp.js

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

/** @license ISC License (c) copyright 2019 original and current authors */
/** @author Ian Hofmann-Hicks (evil) */

var curry = require('../core/curry')
var isDefined = require('../core/isDefined')
var isEmpty = require('../core/isEmpty')
var isNil = require('../core/isNil')
var isInteger = require('../core/isInteger')
var isString = require('../core/isString')
var ref = require('../core/Maybe');
var Nothing = ref.Nothing;
var Just = ref.Just;

function fn(name) {
  function getProp(key, target) {
    if(!(isString(key) && !isEmpty(key) || isInteger(key))) {
      throw new TypeError((name + ": Non-empty String or Integer required for first argument"))
    }

    if(isNil(target)) {
      return Nothing()
    }

    var value = target[key]

    return isDefined(value)
      ? Just(value)
      : Nothing()
  }

  return curry(getProp)
}

var getProp =
  fn('getProp')

getProp.origFn =
  fn

module.exports = getProp