appl-equality.js

const incr = x => x + 1
const add = curry((x, y)) => x + y
const sum3 = curry((x, y, z)) => x + y + z

const maybe1 = Maybe(1)
const maybe2 = Maybe(2)
const maybe3 = Maybe(3)

/* Pada dasarnya, liftA merupakan kombinasi dari map dan ap */

// 1 parameter
liftA(incr, maybe1) == maybe1.map(incr)

// 2 parameter
liftA2(add, maybe1, maybe2) == maybe1.map(add).ap(maybe2)

// 3 parameter
liftA3(sum3, maybe1, maybe2, maybe3) == maybe1.map(sum3).ap(maybe2).ap(maybe3)