Reactogon/Auxiliary/Auxiliary.hs

   1 {-# LANGUAGE Arrows #-}
   2
   3 module Reactogon.Auxiliary.Auxiliary where
   4
   5 import FRP.Yampa
   6
   7
   8
   9 -- Throws an Event when the incoming signal change. The Event is
  10 -- tagged with the new value.
  11 onChange :: (Eq a) => SF a (Event a)
  12 onChange = proc a -> do
  13   b <- onChange' -< a
  14   returnA -< e
  15   where onChange' :: (Eq a) => SF (a,a) Bool
  16         onChange' = arr $ uncurry (==)