MonadExample.hs

module Control.Arrow.MonadExample where

import Control.Arrow.Monad ((>>>=), listen, )
import Control.Arrow.Let ((<<<&), )

import qualified Data.HList as HL

import qualified Control.Arrow.Let as CAL

import Control.Arrow (Arrow, (&&&), (<<<), (<<^), (^>>), )
import Control.Category (id, )

import Prelude hiding (id, )


mix :: Arrow arrow => arrow (a,a) a
mix = undefined

delay :: Arrow arrow => arrow a a
delay = undefined

lowpass :: Arrow arrow => arrow a a
lowpass = undefined


exampleCombinators, exampleBind,
 exampleLet, exampleCase :: Arrow arrow => arrow a a
exampleCombinators =
   mix <<<  id &&& delay  <<< lowpass

exampleBind =
   (\x -> HL.hCons x HL.hNil) ^>>
   ((HL.hHead ^>> lowpass) >>>= \x ->
       mix <<<  listen x &&& (delay <<< listen x))

exampleLet =
   let x :: Arrow arrow => arrow (a,()) a
       x = lowpass <<^ fst
   in  ((mix <<<  CAL.ref x &&& (delay <<< CAL.ref x))  <<<& x)
         <<^ (\i -> (i,()))

exampleCase =
   case lowpass <<^ fst of
      x ->
         ((mix <<<  CAL.ref x &&& (delay <<< CAL.ref x))  <<<& x)
            <<^ (\i -> (i,()))