Currying w/ CoffeeScript

curry.coffee

partial = (fn, args...) ->
  (innerArgs...) ->
    args = args.concat(innerArgs)
    fn(args...)
    
curry = (fn, arity = fn.length) ->
  (args...) ->
    innerFn = (arity) ->
      if arity > 0
        curry partial(fn, args...), arity
      else
        fn(args...)
    innerFn(arity - args.length)

regularFn = (a, b, c) -> a + b + c
regularFn(1, 2, 3)
# -> 6 

curriedFn = curry(regularFn)
curriedFn(1)(2)(3)
curriedFn(1, 2)(3)
curriedFn(1)(2, 3)
curriedFn(1, 2, 3)
# All invocations return -> 6