Hi.

>  I've been using this hackage package "rex" without problems on two
> computers (linux, windows) but now I fail setting it up on a third computer
> which confuses me, and the error message is not really enlightening for me:
>
> $ cabal update
> Downloading the latest package list from hackage.haskell.org
> $ cabal --version
> cabal-install version 1.16.0.2
> using version 1.16.0.3 of the Cabal library
>  $ cabal install rex
> Resolving dependencies...
> cabal: Could not resolve dependencies:
> trying: rex-0.3.1

That's a bad error message indeed ;)

What's your GHC version? Is this an otherwise clean package database?
Can you post the output of "cabal install rex --dry-run -v3"? If the
log is too long to attach to a mailing list mail, just mail it to me
personally.

Cheers,
  Andres