Re: [Haskell-cafe] An exceptional exception
2007/11/8, Andrew Coppin [EMAIL PROTECTED]: Anyway, I wrote a cute little test function for figuring out how each kind of exception works: Hi, could you post your code for this cute test? I would be greatful. Thanks, Radek P.S. Not that I can help, but I'd like to start learning this. -- Codeside: http://codeside.org/ Przedszkole Miejskie nr 86 w Lodzi: http://www.pm86.pl/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] An exceptional exception
Radosław Grzanka wrote: 2007/11/8, Andrew Coppin [EMAIL PROTECTED]: Anyway, I wrote a cute little test function for figuring out how each kind of exception works: Hi, could you post your code for this cute test? I would be greatful. Thanks, Radek P.S. Not that I can help, but I'd like to start learning this. For you (and anybody else who's interested), it can be found here: http://www.hpaste.org/3766 ;-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] An exceptional exception
Well, my problems have now multiplied beyong belief! Allow me to summerise: 1. There exists an I/O exception called invalid parameter, which is not detectable with any of the 8 predicates. (Isn't this what illegal operation is supposed to be for? A general catch-all?) 2. Attempting to open an invalid filename yields the undetectable invalid parameter exception (rather than, say, illegal operation). 3. Attempting to read a directory with an invalid name does the same. 3. Attempting to open a *file* you don't have permission for yields permission error, as expected. However, attempting to read a *directory* yields... invalid parameter again. (Thus, even if this exception were detectable, there's no way to tell the difference between a permission error and a malformed filename.) 4. Not actually related to exceptions, but doesDirectoryExist C:\ yields False. (Even though getDirectoryContents C:\ yields the correct result.) So I can't even use that to filter out invalid directory names. Aaaarrrgh! _ Clearly, making my program give the user meaningful error messages is going to be very hard - unless I resort to trying to *parse* the output of the Show instance for IOError... Does anybody have any helpful hints for me at this point? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] An exceptional exception
On Nov 9, 2007, at 15:01 , Andrew Coppin wrote: 4. Not actually related to exceptions, but doesDirectoryExist C:\ yields False. (Even though getDirectoryContents C:\ yields the correct result.) So I can't even use that to filter out invalid directory names. This is an ancient and extremely annoying general DOS/Windows wart. The root directory has several unexpected behaviors, because it is *not* in fact a directory (or wasn't on FAT, and the behaviors have to be kept for backward compatibility). (You're also not the only one to be frustrated by having to parse stringified I/O exceptions to decipher them.) -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] [EMAIL PROTECTED] system administrator [openafs,heimdal,too many hats] [EMAIL PROTECTED] electrical and computer engineering, carnegie mellon universityKF8NH ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
