moy-fp/test/List/prepend.test.js

A functional programming library.

import __ from '../../src/Function/__'
/**
 * a -> [a] -> [a]
 */
import prepend from '../../src/List/prepend'

test('prpend(not using __)', () => {
  expect(
    prepend(1)([2, 3, 4])
  ).toEqual([1, 2, 3, 4])
})

test('prepend(using __)', () => {
  expect(
    prepend(__, [2, 3, 4])(1)
  ).toEqual([1, 2, 3, 4])
})