Underscore and Camelize in CoffeeScript

underscore_camelize.coffee

each = (arr, func, index=0) ->
  if index < arr.length then [ func(arr[index], index), each(arr, func, index + 1)... ] else []

camelize = (input) ->
  pieces = input.split(/[\W_-]/)
  each(pieces, capitalize).join("")

capitalize = (input) ->
  input.charAt(0).toUpperCase() + input.slice(1)

lowercase = (input) ->
  input.toLowerCase()

underscore = (input) ->
  pieces = input.replace(/([A-Z])/g, '_$1').split(/[\W_-]/).filter (n) -> !!n
  each(pieces, lowercase ).join("_")