Useful higher order functions in CoffeeScript

examples.coffee

add = (x, y) -> x+y
squared = (x) -> x*x

console.log f.curry(add)(1)(2)
console.log f.curry(Array::map, [1,2,3])(squared)

f.flip(f.join)((-> console.log "hi"), (-> console.log "there"))()

f.coffee

f =
  flip: (fn, context = this) ->
    toArray = (x) -> Array::slice.call(x, 0)

    ->
      reversed_args = toArray(arguments).reverse()
      fn.apply(context, reversed_args)

  curry: (->
    append = (x, a) ->
      a.push x
      a

    buildCurried = (fn, arity, args, context) ->
      if arity == 1
        (x) -> fn.apply context, append(x, args)
      else
        (x) -> buildCurried fn, arity-1, append(x, args), context

    (fn, context, arity) ->
      arity ||= fn.length
      context ||= fn
      buildCurried fn, arity, [], context
  )()

  join: () ->
    fns = Array.prototype.slice.call(arguments, 0)

    ->
      args = arguments
      fns.forEach (fn) -> fn.apply(fn, args)