
Attempting $ cabal install persistent Resolving dependencies... In order, the following would be installed: aeson-0.6.0.2 (reinstall) changes: mtl-2.1.1 -> 2.0.1.0 persistent-0.9.0.3 (new package) cabal: The following packages are likely to be broken by the reinstalls: buildwrapper-0.5.2 Use --force-reinstalls if you want to install anyway. Any ideas what is going on ? I believe aeson-0.6.0.2 is already installed. And as far as I can tell the build of aeson-0.6.0.2 doesn't require that specific version of mtl. Am I missing something ? Is there a way to force ghc to ignore this ?? Thanks

My guess would be that persistent indirectly depends on transformers 0.2, since 0.3 is quite new and mtl 2.1.1 doesn't support transformers 0.2. But I can't find which package that is. On May 6, 2012, at 8:46 PM, Graham Berks wrote:
Attempting
$ cabal install persistent Resolving dependencies... In order, the following would be installed: aeson-0.6.0.2 (reinstall) changes: mtl-2.1.1 -> 2.0.1.0 persistent-0.9.0.3 (new package) cabal: The following packages are likely to be broken by the reinstalls: buildwrapper-0.5.2 Use --force-reinstalls if you want to install anyway.
Any ideas what is going on ? I believe aeson-0.6.0.2 is already installed. And as far as I can tell the build of aeson-0.6.0.2 doesn't require that specific version of mtl.
Am I missing something ? Is there a way to force ghc to ignore this ??
Thanks _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
-- Sjoerd Visscher https://github.com/sjoerdvisscher/blog

Hi.
$ cabal install persistent Resolving dependencies... In order, the following would be installed: aeson-0.6.0.2 (reinstall) changes: mtl-2.1.1 -> 2.0.1.0 persistent-0.9.0.3 (new package) cabal: The following packages are likely to be broken by the reinstalls: buildwrapper-0.5.2 Use --force-reinstalls if you want to install anyway.
Any ideas what is going on ? I believe aeson-0.6.0.2 is already installed.
Yes.
And as far as I can tell the build of aeson-0.6.0.2 doesn't require that specific version of mtl.
It doesn't, otherwise it couldn't already be installed. Something persistent depends on in the selected plan depends on mtl-2.0.1.0, and therefore implies the reinstall. It'd be interesting to see the trace of the solver (pass -v3 to the cabal command). You could also try what adding --constraint="mtl == 2.1.1" yields. Cheers, Andres
participants (3)
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Andres Löh
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Graham Berks
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Sjoerd Visscher