Bang patterns in do notation and lambdas

[dons]

Bang patterns in do-notation and lambdas need parentheses around them to parse. This isn't the case for ~ patterns, or bang patterns in let bindings. Seems like a wibble.

{-# OPTIONS -fbang-patterns #-}

-- doesn't work:        A.hs:5:8: Empty 'do' construct
main1 = do
    !c <- return ()
    return ()

-- doesn't work:        A.hs:12:24: parse error on input `!'
main2 = return () >>= \ !c -> return ()



-- does
main3 = do
    (!c) <- return ()
    return ()

-- does
main4 = return () >>= \ (!c) -> return ()


-- does
main5 = let !x = 1 in return ()


-- does
main6 = do
    ~c <- return ()
    return ()

-- does
main7 = return () >>= \ ~c -> return ()

-- dons

[simonpj]

Fixed thank you.