[Haskell-cafe] Cabal bug?

[Duncan Coutts]

On Mon, 2010-01-11 at 13:33 +0100, Henk-Jan van Tuyl wrote:
> L.S.,
> 
> 
> I had a strange response from Cabal:
>    >cabal upgrade hlint
>    Resolving dependencies...
>    cabal: cannot configure containers-0.3.0.0. It requires base >=4.2 && <6
>    For the dependency on base >=4.2 && <6 there are these packages:  
> base-4.2.0.0.
>    However none of them are available.
>    base-4.2.0.0 was excluded because of the top level dependency base -any
> 
> So, base-4.2.0.0 cannot be used, because any version of base is OK? Is  
> this a bug in Cabal?

It's a bug in the sense that the error message is misleading. What it
actually means is "base-4.2.0.0 cannot be used, because an installed
version of base is required". The pretty printing for "installed
constraints" (as opposed to version constraints) is borked.

Duncan