Re: [Haskell-cafe] Bad interface problem.

I am using ghc 7.4.2 which includes template-haskell-2.7.0.0. When I installed QuickCheck-2.5, it requires template-haskell-2.6.0.0. Even I removed all user space packages, the error was still. I think it is a ghc pkg problem, that every package register itself as package:function while ghc (or cabal?) required package-version:function. But --constraint='template-haskell-2.7.0.0' did make it compiled. On Wed, Jul 11, 2012 at 1:34 PM, Claude Heiland-Allen wrote:

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Hi,

On 11/07/12 05:51, Magicloud Magiclouds wrote:

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I cleaned out everything, no luck....

On Fri, Jul 6, 2012 at 2:14 AM, Albert Y. C. Lai wrote:

...

On 12-07-03 04:19 AM, Magicloud Magiclouds wrote:

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template-haskell-2.6.0.0:Language.Haskell.TH differs from name found in the interface file template-haskell:Language.Haskell.TH

You installed a bad template-haskell version. You can only use a version corresponding to your ghc version.

I had a similar problem recently. My solution process was as follows:

1. check which template-haskell version came with my ghc:

$ ghc -V The Glorious Glasgow Haskell Compilation System, version 7.4.2 $ ghc-pkg list template-haskell /home/claude/opt/lib/ghc-7.4.2/package.conf.d template-haskell-2.7.0.0 /home/claude/.ghc/x86_64-linux-7.4.2/package.conf.d $

2. make sure to forbid every other version of template-haskell (because it will break horribly, as you found):

$ cabal install --constraint='template-haskell==2.7.0.0' foo

3. if foo fails to install because it thinks it needs a different version of template-haskell, try adjusting dependencies in foo.cabal

4. if foo installs and works with the adjusted dependencies, let the maintainer know

...

...

I think things are so messed up that it is time to clean out everything. See my http://www.vex.net/~trebla/haskell/sicp.xhtml#remove

In fact, time to read the whole article and avoid unsafe re-installs and "upgrades".

It's a good read for sure! Perhaps it could be updated to add a problem I ran into recently:

"cabal install --solver=modular --avoid-reinstalls" sounds perfect, if sicp.xhtml scared you properly. But excessively avoiding reinstalls is bad, as cabal-install seems to install a different allowable version instead. The result for me was horrible diamond dependency problems - half my packages were built with one version of mtl/transformers, and the other half with a different version of mtl/transformers.

When I then tried to ghci using some modules from both halves of my installed packages, I got very very confusing type errors complaining about almost-identical-looking types not being identical.

Claude -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux)

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