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Günther Schmidt

10 Jan 2010 10 Jan '10

9:44 p.m.

Hi, when I cabal-installed the iteratee package, the transformers package was also installed as a dependency. Now when I run applications that import Control.Monad.Transformers I get this: Could not find module `Control.Monad.Trans': it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2 What's the work around for situations like this? Günther

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Ivan Lazar Miljenovic

10 Jan 10 Jan

9:49 p.m.

Günther Schmidt writes:

Could not find module `Control.Monad.Trans': it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2

There's a way of specifying it at the top of whichever file you're using, but so far my workaround in this situation is to use "ghc-pkg hide" on whichever of those packages I don't use in my code. -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com

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Günther Schmidt

9:59 p.m.

Hi Ivan, ghc-pkg hide works fine, thanks! Günther Am 11.01.10 03:49, schrieb Ivan Lazar Miljenovic:

Günther Schmidt writes:

...
Could not find module `Control.Monad.Trans': it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2

There's a way of specifying it at the top of whichever file you're using, but so far my workaround in this situation is to use "ghc-pkg hide" on whichever of those packages I don't use in my code.

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Valery V. Vorotyntsev

11 Jan 11 Jan

2:54 a.m.

...
Günther Schmidt:

...
Could not find module `Control.Monad.Trans': it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2

Ivan Lazar Miljenovic:

...
There's a way of specifying it at the top of whichever file you're using, but so far my workaround in this situation is to use "ghc-pkg hide" on whichever of those packages I don't use in my code.

Günther Schmidt:

ghc-pkg hide works fine, thanks!

As an alternative, you can use `LANGUAGE PackageImports' pragma: | {-# LANGUAGE PackageImports #-} | | import "transformers" Control.Monad.Trans See http://thread.gmane.org/gmane.comp.lang.haskell.libraries/12134/focus=12155 PS: Have fun with iteratees! -- vvv

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Martijn van Steenbergen

4:03 a.m.

Günther Schmidt wrote:

Hi,

when I cabal-installed the iteratee package, the transformers package was also installed as a dependency.

Now when I run applications that import Control.Monad.Transformers I get this:

Could not find module `Control.Monad.Trans': it was found in multiple packages: transformers-0.1.4.0 mtl-1.1.0.2

Another solution is to build your applications using Cabal and specify your dependency on mtl in the cabal file. HTH, Martijn.

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Ivan Lazar Miljenovic

4:11 a.m.

Martijn van Steenbergen writes:

Another solution is to build your applications using Cabal and specify your dependency on mtl in the cabal file.

But until we have "cabal ghci", this completely fails for actual hacking purposes... -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com

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Sittampalam, Ganesh

4:16 a.m.

Ivan Lazar Miljenovic wrote:

Martijn van Steenbergen writes:

...
Another solution is to build your applications using Cabal and specify your dependency on mtl in the cabal file.

But until we have "cabal ghci", this completely fails for actual hacking purposes...

Just do cabal build -v, then cut and paste the ghc --make command-line and replace --make with --interactive. Obviously rather a hack, but remarkably usable in practice, in my experience. Ganesh =============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ===============================================================================

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Bas van Dijk

6:07 a.m.

On Mon, Jan 11, 2010 at 10:16 AM, Sittampalam, Ganesh wrote:

Ivan Lazar Miljenovic wrote:

...
Martijn van Steenbergen writes:

...
Another solution is to build your applications using Cabal and specify your dependency on mtl in the cabal file.

But until we have "cabal ghci", this completely fails for actual hacking purposes...

Just do cabal build -v, then cut and paste the ghc --make command-line and replace --make with --interactive.

Thanks for this tip! I always make a ghci.sh bash script in each of my projects that calls "ghci -hide-all-packages -package x -package y -package z". However a "cabal ghci" or "cabal interactive" command that does this automatically would be ideal. I see there already is a ticket[1] about it. regards, Bas [1] http://hackage.haskell.org/trac/hackage/ticket/382

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Valery V. Vorotyntsev

8:02 a.m.

Bas van Dijk wrote:

I always make a ghci.sh bash script in each of my projects that calls "ghci -hide-all-packages -package x -package y -package z". However a "cabal ghci" or "cabal interactive" command that does this automatically would be ideal. I see there already is a ticket[1] about it.

regards, Bas

[1] http://hackage.haskell.org/trac/hackage/ticket/382

Shell script can be replaced with .ghci file. See http://neilmitchell.blogspot.com/2010/01/using-ghci-files-to-run-projects.ht... (Just my two cents.) -- vvv

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participants (6)

Bas van Dijk
Günther Schmidt
Ivan Lazar Miljenovic
Martijn van Steenbergen
Sittampalam, Ganesh
Valery V. Vorotyntsev