frp.coffee

fromCallback = (fn) ->
  stream = []
  cb = -> 
    for cb in stream
      cb.apply @, arguments
  fn cb
  stream

map = (fn) -> (stream) -> 
  result = []
  stream.push ->
    mapped = fn.apply @, arguments
    for cb in result 
      cb mapped
  result

filter = (fn) -> (stream) -> 
  result = []
  stream.push ->
    if fn.apply @, arguments
      for cb in result 
        cb.apply @, arguments
  result

flatMap = (fn) -> (stream) ->
  result = []
  stream.push ->
    newStream = fn.apply @, arguments
    newStream.push ->
      for cb in result 
        cb.apply @, arguments
  result

subscribe = (fn) -> (stream) ->
  stream.push -> fn.apply @, arguments

# TEST

c_ = null
stream = fromCallback (c) -> c_ = c
mapped = map((val) -> val + 'bar')(stream)
filtered = filter((val) -> true)(mapped)
c_2 = null
flatMapped = flatMap(
  (val) -> fromCallback (cb) -> c_2 = (a) -> cb val, a
)(filtered)
subscribe(-> console.log.apply(console,arguments))(flatMapped)
c_('foo')
c_2('baz')