On Wed, Oct 21, 2009 at 3:29 AM, Michael Mossey <m...@alumni.caltech.edu> wrote: > The examples in the "error handling" chapter (19) of RWH don't run under GHC > 6.10. > > For instance, an example might be > > main = handle (\_ -> putStrLn "error") (print $ 5 `div` 0) > > Trying to load this results in "amigous type variable 'e' in the constraint: > 'Exception e' arising from a use of 'handle' etc etc. > > I was able to fix this via the ludicrously complex: > > main2 = (handle :: (SomeException -> IO ()) -> IO () -> IO ()) > (\_ -> putStrLn "Error calculating result") > (print $ 5 `div` 0) > > Is there a more concise way to use "handle", or can someone point me to a > tutorial that might explain the changes in 6.10 and in a general way how to > get the RWH examples to run?
How about: anyHandler :: IO () -> SomeException -> IO () anyHandler = const main = handle (anyHandler (putStrLn "Error calculating result")) (print $ 5 `div` 0) Luke _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
