[Haskell-beginners] Missing or recursive dependencies

[Daniel Fischer]

On Thursday 02 September 2010 11:31:01, Lyndon Maydwell wrote:
> Hi beginners.
>
> I'm getting an odd problem quite a lot recently:
>
> ghc -fglasgow-exts --make -O2 -W X.hs -v -o X
>
> package Cabal-1.8.0.6-ec9be469687b5a514f4b7e8e2b8343c7 is shadowed by
> package Cabal-1.8.0.6-c995b90190c27e1dfa2ab3d5434fabef

You have two versions of Cabal-1.8.0.6, probably you should unregister the 
one in the user-db.

Anyway, run ghc-pkg check first. Fix what that reports as broken by 
unregistering/reinstalling.
Since what is shown below all directly or indirectly traces to ghc-6.12.3, 
which depends on Cabal-1.8.0.6, your two versions of that are probably the 
root cause, so I'd start with Cabal.

> package QuickCheck-2.1.1.1-c7435cb0d5b5de72fe9540c48335606d is
> unusable due to missing or recursive dependencies:
>   ghc-6.12.3-66a382195c8a71849653439b67021fd1
> package bin-package-db-0.0.0.0-0dffb74a73bb78b5dc02ca941bbcbea0 is
> unusable due to missing or recursive dependencies:
>   Cabal-1.8.0.6-ec9be469687b5a514f4b7e8e2b8343c7
> package category-extras-0.53.5-ee54cd5c810a6c004a1b7a276d0e0076 is
> unusable due to missing or recursive dependencies:
>   ghc-6.12.3-66a382195c8a71849653439b67021fd1
> package comonad-random-0.1.2-897a5da683d269c3b2db3e03ac43279b is
> unusable due to missing or recursive dependencies:
>   category-extras-0.53.5-ee54cd5c810a6c004a1b7a276d0e0076
> ...
>
> I've asked on irc, and the consensus is that something is very wrong,
> however we weren't able to diagnose the cause. It would probably be
> worth looking at on-list for future reference.
>
> Does anyone have any ideas?