each :: (a → Undefined) → [a] → [a]Applies a function to each item in the list and returns the original list. Used for side effects.
each((x) => x.push('boom'), [['a'], ['b'], ['c']]);
//=> [['a', 'boom'], ['b', 'boom'], ['c', 'boom']]map :: (a → b) → [a] → [b]Applies a function to each item in the list, and produces a new list with the results. The length of the result is the same length as the input.
map((x) => x + 1, [1, 2, 3]);
//=> [2, 3, 4]