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

A functional programming library.

import __ from '../../src/Function/__'
/**
 * Maybe m => b -> (a -> b) -> m a -> b
 */
import maybe from '../../src/Functor/maybe'
import Maybe from '../../src/Functor/Maybe/index'

test('maybe(not using __), null', () => {
  expect(
    maybe(1)(x => x + 1)(Maybe.of(null))
  ).toBe(1)
})

test('maybe(not using __), not null', () => {
  expect(
    maybe(1)(x => x + 1)(Maybe.of(12))
  ).toBe(13)
})

test('maybe(using __), not null', () => {
  expect(
    maybe(1, __, Maybe.of(12))(x => x + 1)
  ).toBe(13)
})