moy-fp/src/Functor/lift.js

A functional programming library.

import nAry from '../Function/nAry'
import map from '../Functor/map'
import ap from '../Functor/ap'

/**
 * Functor f => ((a, b, ..., m) -> n) -> ((f a, f b, ..., f m) -> f n)
 */
const lift = fn => nAry(fn.length, (arg, ...args) => {
  switch(Object.prototype.toString.call(arg)){
    case '[object Array]':
    case '[object Identity]':
    case '[object Maybe]':
    case '[object IO]':
    case '[object Task]': return args.reduce(
      ap,
      map(fn, arg),
    )
    default: return
  }
})

export default lift