Question

I tried installing Djinn by using cabal but got the following error –

$ cabal install djinn --verbose
Reading available packages...
Resolving dependencies...
cabal: cannot configure djinn-2009.9.3. 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

The error message is mysterious, shouldn’t base -any allow base version 3.0.3.1?

Answer 1

From the Haskell Mailing list:

It’s not a great error message. 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.

Hope that helps.