[Haskell-cafe] Control.Exception Funny

[Dominic Steinitz]

Claus Reinke wrote:
> btw, if your handler cannot return the same type as your action, is this
> the right place to catch the exceptions?
> 

That was an example, the real code looks something like this:

>    do d <- getCurrentDirectory
>       t <- getCurrentTime
>       let u = "asn1c." ++ show (utctDay t) ++ "." ++ show (utctDayTime t)
>       createDirectory u
>       setCurrentDirectory u
>       CE.catch (do writeASN1AndC (genFile <.> "asn1") (genFile <.> "c") ty val
>                    runCommands [(asn1c ++ " " ++ asn1cOptions ++ " " ++ skeletons ++ " " ++ (genFile <.> "asn1"), "Failure in asn1c")]
>                    d <- getCurrentDirectory
>                    fs <- getDirectoryContents d
>                    let cFiles = 
>                           case os of
>                              "mingw32" -> 
>                                 (genFile <.> "c"):(name <.> "c"):(cFiles' ["converter-sample.c"] ".c.lnk" fs)
>                              _ ->
>                                 (genFile <.> "c"):(name <.> "c"):(cFiles' [genFile <.> "c", name <.> "c", "converter-sample" <.> "c"] ".c" fs)
>                    putStrLn (show cFiles)
>                    putStrLn (show (map compile cFiles))
>                    runCommands (map compile cFiles)
>                    putStrLn (linker ++ " " ++ linkerOut genFile ++ " " ++ ("*" <.> objectSuffix))
>                    runCommands [
>                       (linker ++ " " ++ linkerOut genFile ++ " " ++ ("*" <.> objectSuffix), "Failure linking"),
>                       ((executable genFile) ++ " " ++ (genFile <.> "per"), "Failure executing")
>                       ]
>                    readGen (genFile <.> "per") ty)
>                (\e -> hPutStrLn stderr ("Problem with generating / compiling\n" ++ show e))
>       setCurrentDirectory d

Your suggestion:

> you'll see 'IOException' listed, so 'show (e::IOException)' might do
> what you want.

works perfectly.

Thanks very much, Dominic.