1{-# LANGUAGE Arrows #-}
2
3bar f = proc a -> do
4  b <- f -< a
5
6barbar f g = proc a -> do
7  b <- f -< a
8  returnA -< b
9
10barbaz f g = proc (a, b) -> do
11  c <- f -< a
12  d <- g -< b
13
14bazbar f = proc a -> do
15  a <-
16    f
17      -<
18        a
19