moy-fp/test/Functor/lift.test.js

A functional programming library.

import __ from '../../src/Function/__'
import add from '../../src/Math/add'
/**
 * Functor f => ((a, b, ..., m) -> n) -> ((f a, f b, ..., f m) -> f n)
 */
import lift from '../../src/Functor/lift'
import Identity from '../../src/Functor/Identity/index'

/**
 * you should not use this similar funciton to get value anywhere in your application
 * if you must need the inner value, you may need Comonad
 * here is just simple for test
 */
const inspect = x => `Identity(${x.value})`

test('lift(not using __), array', () => {
  expect(
    lift(add)([1, 2])([3, 4])
  ).toEqual([4, 5, 5, 6])
})

test('lift(not using __), Identity', () => {
  expect(
    inspect(lift(add)(Identity.of(1))(Identity.of(2)))
  ).toEqual(inspect(Identity.of(3)))
})


test('lift(not using __), number', () => {
  expect(
    lift(add)(1)(2)
  ).toBeUndefined()
})

test('lift(using __), array', () => {
  expect(
    lift(add)(__, [3, 4])([1, 2])
  ).toEqual([4, 5, 5, 6])
})