[Haskell-cafe] Hackage: Tarball and package description of package mtl differ
Björn Peemöller
I just wanted to install the mtl package for GHC 8.0.1-rc2, but
installation failed with
Setup: Encountered missing dependencies:
transformers ==0.4.*
Taking a look at the package description [1], it specifies
build-depends: base < 6, transformers >= 0.4 && < 0.6
but the Cabal description in the tarball [2] says
build-depends: base < 6, transformers == 0.4.*
Strangely, if I execute
$ cabal unpack mtl-2.2.1
I obtain a version with the same specification as [1].
Does anybody has an explanation for this?
Regards,
Björn
[1]: http://hackage.haskell.org/package/mtl-2.2.1/mtl.cabal
[2]: http://hackage.haskell.org/package/mtl-2.2.1/mtl-2.2.1.tar.gz
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Adam Bergmark
Björn Peemöller
> This is because a revision to the cabal file was published[1]. Tarballs
> always stay the same (because of possible signing, etc) but
> cabal-install will use the revised metadata when doing most of its
> operation including `install', `get', and `unpack'.
Hi Adam,
thank you for the explanation. I tried to install cabal-install taken
from GitHub for GHC 8.0.0.rc2 via the included `bootstrap.sh` script,
which essentially obtains the tarball from hackage using `curl` and then
calls
$ cd mtl-2.2.1
$ ghc --make Setup.hs -o Setup
$ ./configure # + additional options
> You don't say how you are trying to install mtl, is it not through
> Cabal? Either way, make sure to use the revised cabal file and it
> should be fine.
Okay, I will then install mtl by hand and try the bootstrap script
afterwards.
Thanks,
Björn