Temporarily overriding Data.Generic

José Pedro Magalhães jpm at cs.uu.nl
Thu Feb 5 02:43:52 EST 2009

Hi Deniz,

On Thu, Feb 5, 2009 at 00:11, Deniz Dogan <deniz.a.m.dogan at gmail.com> wrote:

> Sorry for those who receive this who have already gotten it from
> haskell-cafe.
> ---
> Hi
> I'm currently working on "hacking" Data.Generics for my master thesis.
> I'm basically trying to find out whether it can be made any faster
> using e.g. rewrite rules.

Great! Please let us know of the results when you have them :-)

> The problem I'm having is that I need an
> easy way to import my own modified version of Data.Generics (currently
> located in the same directory as my testing program) without
> unregistering or hiding syb- as base seems to depend on it.
> I've read the GHC user manual trying to find nice ways to do this
> using a bunch of different parameters to ghc, but I can't figure it
> out. Does anyone here know?

I've had my own problems while developing a successor version of the syb
package. For starters, cabal fails to install the package:

>cabal install
Resolving dependencies...
cabal: dependencies conflict: base- requires syb == however
syb- was excluded because syb- was selected instead
syb- was excluded because of the top level dependency syb ==

Note that this package explicitly requires base >= 4.0. Anyway, runghc
Setup.hs install does it, though. However, after having it installed I can't
use it, getting this when any module imports Data.Generics:

    Bad interface file: C:\Program Files
        Something is amiss; requested module  syb:Data.Generics differs from
name found in the interface file syb-
Failed, modules loaded: none.

I talked about this on IRC before and remember this might have had something
to do with syb having been unversioned in the release of GHC 6.10.1. But I
hope someone can clarify this better...


> Any help appreciated,
> Deniz
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> Glasgow-haskell-users at haskell.org
> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
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