[Haskell-cafe] RE: ANN: System.FilePath 0.9

Brian Smith brianlsmith at gmail.com
Mon Jul 17 17:10:01 EDT 2006


Hi Neil,

On 7/17/06, Neil Mitchell <ndmitchell at gmail.com> wrote:
>
> Hi Brian,
>
> You sent this email just to me, and not to the list. If you indended
> to send to the list then feel free to forward my bits on to the list.
>
>
> > I know that FilePath is defined by Haskell '98 as a String and so it
> cannot
> > be changed. So, perhaps a new type or class should be created for this
> > library (hereafter "GoodPath," although I am not suggesting that is the
> best
> > name).
> The problem is people will have to marshal their data into this
> GoodPath, and marshal it out again. When people can shortcut that
> marshalling, as the current readFile/writeFile definitions ensure they
> can, they will. At that point you loose all safety because people will
> abuse it.


I disagree. It would be trivial to create a new module that exported new
definitions of file IO actions that operated on "GoodPath" instead of
"FilePath," transparently delegating to the original readFile/writeFile/etc.
until they could be removed in the future. This would also support the
"SuperFilePath" idea you mentioned.

Another thing I thought of would be a "canonicalPath" IO action
(canonicalPath :: FilePath -> IO FilePath) that returns a FilePath that
implements case-preserving-case-insensitive matching. For example, if there
is a file named "Hello There.txt" in C:\, then
(canonicalPath "c:\hello there.txt ") would give "C:\Hello There.txt").

I think that the xxxDrive functions should only be exported from
System.FilePath.Windows and no System.FilePath since it is unclear as to how
they should be used effectively by cross-platform software.

- Brian
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