{-# OPTIONS_GHC -farrows -fno-monomorphism-restriction -fglasgow-exts #-}

module Foo where

import Control.Arrow

data Pair a b = a :# b

counter =
   proc x ->
     do t :# _ <- undefined -< x
        rec (cnt:: Int) <- undefined -< undefined
            undefined -< show cnt
        returnA -< undefined