moy-fp/test/Function/o.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * (b -> c) -> (a -> b) -> a -> c
 */
import o from '../../src/Function/o'

test('o(not using __)', () => {
  expect(
    o(x => x * 3, x => x + 1, 3)
  ).toBe(12)
})

test('o(using __)', () => {
  expect(
    o(x => x * 3, __, 3)(x => x + 1)
  ).toBe(12)
})