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

Andrew Pimlott andrew at pimlott.net
Thu Jul 27 14:13:48 EDT 2006

On Wed, Jul 26, 2006 at 05:06:41PM -0400, David Roundy wrote:
> cp(1), for example, treats paths with trailing separators differently
> from paths without.
> This doesn't apply uniformly to all programs--except that we can say
> that any path with a trailing '/' is intended to be a directory, and
> if it's not, then that's an error.  But the trouble is that if you
> silently drop the '/', then the only way for me to implement a correct
> cp(1) in Haskell is to not use your proposed interface for pathname
> handling, which drops this information.

I thought some more about this, and I think the right way to handle this
is on parsing and printing.  After all, the trailing slash has no real
meaning for any intermediate processing you might do.  So if the type
used by my path operations is Path, I might have something like

    readPath :: String -> (Path, Bool {- trailing delimiter -})
    showPath :: Path -> String
    showPathTrailingSlash :: Path -> String

This is far simpler than trying to figure out what the slash means for
every path operation.


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