{-# LANGUAGE Arrows #-}

foo f g = proc (x, y) -> do
    rec a <- f y -< x
        b <-
            g x
                -<
                    y
    bar
        -<
            ( a
            , b
            )
    rec p <-
            f
                p
                -<
                    a
    rec q <-
            g
                q
                -<
                    b