BangPatterns + ViewPatterns

This program:

{-# LANGUAGE ViewPatterns, BangPatterns #-}

import Control.Exception

main :: IO ()
main = do print (f False)
          print (f True)
          print (g undefined) `catchE` \_ -> putStrLn "g exception"
          print (h undefined) `catchE` \_ -> putStrLn "h exception"
          print (i undefined) `catchE` \_ -> putStrLn "i exception"
          putStrLn "Done"

f :: Bool -> String
f (view -> Nothing) = "Got Nothing"
f (view -> Just x)  = "Got Just " ++ show x

g :: Bool -> String
g (view -> x) = "g Got something"

h :: Bool -> String
h (view -> !x) = "h Got something"

i :: Bool -> String
i !(view -> x) = "i Got something"

view :: Bool -> Maybe Int
view False = Nothing
view True = Just 5

catchE :: IO a -> (ErrorCall -> IO a) -> IO a
catchE = catch

prints:

"Got Nothing"
"Got Just 5"
"g Got something"
"h exception
"i Got something"
Done

but presumably i ought to be strict in x.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture