Pre-proposal discussion: add a version of dropWhileEnd with different laziness properties to Data.List

John Lato jwlato at
Mon Sep 29 20:47:49 UTC 2014

On Sep 29, 2014 6:19 AM, "Felipe Lessa" <felipe.lessa at> wrote:
> On 28-09-2014 22:38, John Lato wrote:
> > I don't think we should be encouraging the use of Data.Sequence for file
> > paths.  An opaque OS-specific structure seems like the natural choice
> >
> > (Incidentally I'd like to develop this as a userland library, if anyone
> > would step forward to help with the Windows-specific stuff)
> Do you mean system-filepath [1]?

No.  The api is ok, but performance is terrible because everything is a
String.  Traversing large directories in Haskell is orders of magnitude
slower than it should be (unless you use posix-paths, which obviously isn't
portable).  I mean something that internally uses a RawFilePath on posix
systems and some windows-specific thing on Windows.
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