appAlt env es (PCon c,e)        = case skipLambda (conArity env c) e es of
                                    Just e' -> Just (PCon c, e')
                                    _       -> Nothing
appAlt env es (PCon c,e)        = case skipLambda (conArity env c) e es of
                                    Just e' -> Just (PCon c, e')
                                    _       -> Nothing
appAlt env es (PCon c,e)        = case skipLambda (conArity env c) e es of
                                    Just e' -> Just (PCon c, e')
                                    _       -> Nothing