[Haskell-cafe] Cabal: top level dependency base -any

[Andres Loeh]

Hi.

> Could anyone shed light on the meaning of this error message?
>
> cabal: cannot configure xmonad-0.9.1 It requires base ==3.*
> For the dependency on base ==3.* there are these packages: base-3.0.3.1 and
> base-3.0.3.2. However none of them are available.
> base-3.0.3.1 was excluded because of the top level dependency base -any
> base-3.0.3.2 was excluded because of the top level dependency base -any

It's not a great error message. Yes, xmonad-0.9.1 requires base ==3.*.
So far, so good. Now, base is a special package. It comes with ghc,
and cannot be upgraded. That's why Cabal will rule out all base
versions but the one you already have installed. If you have a recent
ghc, that'll be base-4.

So Cabal is correct to fail in this case: you cannot install this
version of xmonad with this version of ghc. But yes, the error message
could (and hopefully soon will) be improved.

Cheers,
  Andres