immutable array examples

immutables.js

const clone     = x => [...x]
const push      = y => x => [...x, y]
const pop       = x => x.slice(0,-1)
const unshift   = y => x => [y, ...x]
const shift     = x => x.slice(1)
const sort      = f => x => [...x].sort(f)
const delete    = i => x => [...x.slice(0,i), ...x.slice(i+1)]
const splice    = (s,c,...y) => x => [...x.slice(0,s), ...y, ...x.slice(s+c)]
const unique    = arr => [...new Set(arr)]

const {0:first, length:l, [l - 1]:last} = [1,2,3,4,5]

usage:

clone([1,2,3])
push(4, [1,2,3])
pop([1,2,3])
unshift(0, [1,2,3])
shift([1,2,3])
sort((a,b) => {...}, [1,2,3])
delete(1, [1,2,3])
splice(1, 2, [1,2,3])  
unique([1,1,2,3,4,5])