[Haskell-cafe] Re: Suggested additions to System.FilePath.Posix/Windows

Hello Neil, Thanks for the pointer Neil. I will read the site. Besides, it allows me to submit a fixed version since I just found a bug! Cheers, - Marcus P.S. 452 black box tests of my little command utility, and I still forgot about a corner case. Now there are 454 black box test cases :). Neil Mitchell wrote:

Hi Marcus,

Thanks for your suggestions. I'm a Windows user so aren't really qualified to comment on these suggestions - it depends what Posix users would like. I suggest you follow the Library Submission Process - filepath is now a core library, and as such I don't have the freedom/power to change it as I like, and it's generally something lots of people should think about.

http://www.haskell.org/haskellwiki/Library_submissions

Thanks

Neil

PS. I'm off for 3 weeks starting very soon, so will be unlikely to reply to any email thread for a long time :-)

On Thu, Sep 17, 2009 at 10:58 AM, Marcus D. Gabriel wrote:

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Hello Neil

I used System.FilePath.Posix quite extensively recently, and I thank you for the package filepath. There were however two words that I needed which I could not construct from those in System.FilePath.Posix. They are maybe of interest to you and others.

I submit these two words to you for consideration for inclusion in System.FilePath.Posix. Please change the names as you see fit.

I do not know if they make sense for System.FilePath.Windows. If the do not make sense, then please feel free to drop them so as to preserve the interface.

As requested, I Cc'ed the haskell-cafe, but I am not at the moment following these threads, so if anyone else responds, please Cc me if you wish.

Thanks again and cheers, - Marcus

P.S. Here they are. Although I use ksh(1) as an example, this is a feature of POSIX shells.

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-- | 'reduceFilePath' returns a pathname that is reduced to canonical -- form equivalent to that of ksh(1), that is, symbolic link names are -- treated literally when finding the directory name. See @cd -L@ of -- ksh(1). Specifically, extraneous separators @(\"/\")@, dot -- @(\".\")@, and double-dot @(\"..\")@ directories are removed.

reduceFilePath :: FilePath -> FilePath reduceFilePath = joinPath . filePathComponents

This is in turn built on filePathComponents that does all the work.

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filePathComponents :: FilePath -> [FilePath] filePathComponents "" = [] filePathComponents (c:cs) = reverse $ snd $ foldl accumulate (if c == pathSeparator then ([],["/"]) else ([c],[])) (cs++[pathSeparator]) where accumulate :: (String,[String]) -> Char -> (String,[String]) accumulate (cs, css) c = if c == pathSeparator then ([],(if null cs then id else cons cs) css) else (cs++[c],css) cons :: String -> [String] -> [String] cons cs css | cs == "." = css | cs /= ".." || null css = cs : css | otherwise = let hd = head css tl = tail css in if hd == [pathSeparator] then css else if hd == ".." then cs : css else if null tl then ["."] else tl -- Marcus D. Gabriel, Ph.D. Saint Louis, FRANCE http://www.marcus.gabriel.name mailto:marcus@gabriel.name Tel: +33.3.89.69.05.06 Portable: +33.6.34.56.07.75