1{-# LANGUAGE Arrows #-}
2
3bar f = proc a ->
4  do b <- f -< a
5
6barbar f g = proc a ->
7  do b <- f -< a
8     returnA -< b
9
10barbaz f g = proc (a, b) ->
11  do c <- f -< a
12     d <- g -< b
13
14bazbar f = proc a ->
15  do a
16       <-
17       f
18       -<
19       a
20
21