[Hs-Generics] EMGM for GHC 6.12

[Antoine Latter]

The error message you're getting is pretty un-helpful - what's
happened is that EMGM has declared that it is only compatible with
template-haskell version 2.3, however GHC 6.12 ships with
template-haskell version 2.4. So caball helpfully tries to install the
older version of template-haskell and fails. (for the curious, if you
get packed-string to install, installing template-haskell 2.3 will
still result in misery, as it is a "magic" package which relies on
being installed at the same time as GHC - there's no simple way to
have multiple versions working).

To get a better error message, you'll want to edit the EMGM package
description and allow it to try and build with template-haskell 2.4
(this will be the file names 'emgm.cabal').

Antoine


On Mon, Oct 4, 2010 at 11:36 PM, Hans Peter Würmli <wurmli at hispeed.ch> wrote:
>
> I tried to install EMGM from Hackagedb under ghc 6.12.1 (Debian Packages).
> The process ends with:
>
> "...
> Building packedstring-0.1.0.1...
>
> Data/PackedString.hs:83:7:
>     Could not find module `Data.Data':
>       It is a member of the hidden package `base'.
>       Perhaps you need to add `base' to the build-depends in your .cabal
> file.
>       Use -v to see a list of the files searched for.
> cabal: Error: some packages failed to install:
> emgm-0.3.1 depends on packedstring-0.1.0.1 which failed to install.
> packedstring-0.1.0.1 failed during the building phase. The exception was:
> ExitFailure 1
> template-haskell-2.3.0.1 depends on packedstring-0.1.0.1 which failed to
> install."
>
> Also I noticed that the last upload was version 0.3.1. Is the library still
> under maintenance?
>
> Cheers
>
> Hans Peter
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