[Haskell-cafe] How to cabal fetch mtl==2.0.0.0?

[Iain Alexander]

On 25 Nov 2010 at 23:48:27, Ross Paterson wrote:

> On Fri, Nov 26, 2010 at 12:24:26AM +0100, Bas van Dijk wrote:
> > Maybe it helps if special-functors gets an upper bound on its mtl
> > dependency: mtl < 2.
> 
> It should have mtl < 1.1.1.0, because that version lacks one of the
> instances it relies on.
> 

Well, that certainly breaks the dependency loop, but still leaves the overall 
fetch broken.

<log>
C:\Source\Haskell\Wrapper>cabal fetch mtl-2.0.0.0
Resolving dependencies...
cabal: cannot configure special-functors-1.0.0.1. It requires mtl >=1.0 &&
<1.1.1
For the dependency on mtl >=1.0 && <1.1.1 there are these packages: mtl-1.0,
mtl-1.1.0.0, mtl-1.1.0.1 and mtl-1.1.0.2. However none of them are available.
mtl-1.0 was excluded because mtl-2.0.0.0 was selected instead
mtl-1.0 was excluded because of the top level dependency mtl ==2.0.0.0
mtl-1.1.0.0 was excluded because mtl-2.0.0.0 was selected instead
mtl-1.1.0.0 was excluded because of the top level dependency mtl ==2.0.0.0
mtl-1.1.0.1 was excluded because mtl-2.0.0.0 was selected instead
mtl-1.1.0.1 was excluded because of the top level dependency mtl ==2.0.0.0
mtl-1.1.0.2 was excluded because mtl-2.0.0.0 was selected instead
mtl-1.1.0.2 was excluded because of the top level dependency mtl ==2.0.0.0
</log>

I've tried installing transformers-0.2.2.0, but that doesn't seem to help 
either.
Ah, but running with --verbose=3 shows that it's using the 6.4.1 version of ghc-
pkg, which doesn't have transformers-0.2.2.0 installed, and if it did would 
have the dependency on special-functors.  I'm fairly sure I've got a pre-built 
cabal command-line binary, the 6.12.3 version of ghc-pkg is first on the PATH, 
and there's nothing relevant in ~/cabal/config (I'm on Windows, but we all know 
what I mean by that).  So where's it getting the 6.4.1 ghc-pkg from?  I've 
tried overriding --with-hc-pkg=..., but it's an unrecognized option.
-- 
Iain Alexander      ia at stryx.demon.co.uk