const double = x => x * 2
const getLength = string => string.length

const map = (collection, fn) => collection.map(fn)

const messages = ['Hello', 'Bye']

const mapToLengths = collection => map(collection, getLength)
const mapToDoubles = collection => map(collection, double)
const pipe = (...fns) => input => fns.reduce((mem, fn) => fn(mem), input)

const doubleLengths = pipe(mapToLengths, mapToDoubles)(messages)