JavaScript Async function compositions through the Continuation Monad

ContM.js

//    unit :: a -> m a
const unit = x => c => c (x)

//    bind :: m a -> (a -> m b) -> m b
const bind = m => f => c => m (x => f(x)(c))

//    map :: ma -> (a -> b) -> m b
const map = m => f => bind (m) (x => unit(f(x)))

 //   foldr :: (a -> b -> b) -> b -> [a] -> b
const foldr = f => acc => xs => (xs.length == 0) ? acc : f(xs[0]) (foldr(f)(acc)(xs.slice(1)))

//    flip :: (a -> b -> c) -> (b -> a -> c)
const flip = f => x => y => f (y) (x)

//    sequence :: m b -> [a -> m b] -> m b
const sequence = acc => ms => foldr (flip (bind)) (acc) (ms)

// Sample usage

const f = x => unit(x + 3)

const g = x => unit(x * 2)

const h = x => unit("Number " + x)

const k = sequence (unit(4)) ([h, g, f])

k(x => console.log("result: " + x))