some useful funcs

RandomFuncs.js

let pipe = (...funcs) => (...args) => funcs.reduce((vals, func) => (
	vals === args ? func(...vals) : func(vals)
), args)

let curry = (func) => function newCurry (...args) {
	return args.length < func.length ? newCurry.bind(null, ...args) : func.bind(null, ...args)()
}()

let map = curry((func, arr) => {
	let l = arr.length
	let newArr = []
	while(l--) {
	  newArr[l] = func(arr[l])
	}
	return newArr
})

let reduce = curry((func, arr, init = null) => {
	let acc = init
	for(let i = 0, x; x = arr[i]; ++i) {
	  acc = func(acc, arr[i], i, arr)
	}
	return acc
})

let flatten = (arr) => reduce((acc, val) => (
	acc.concat(Array.isArray(val) ? flatten(val) : val)
), arr, [])