Javascript one-liner recursive map/reduce implementation

mapreduce.js

function map(arr, func) { return arr.length <= 1 ? [func(arr[0])] : [func(arr[0])].concat(map(arr.slice(1), func)) }    
function reduce(arr, func, start) { return arr.length <= 1 ? func(arr[0], start) : func(arr[0], reduce(arr.slice(1), func, start)); }   

So memory hungry, but so fast to write.