[Haskell-cafe] Cabal problem, broken packages?

[Tom Ellis]

On Thu, Sep 15, 2022 at 06:11:55PM +0200, Volker Wysk wrote:
> Am Donnerstag, dem 15.09.2022 um 16:31 +0100 schrieb Tom Ellis:
> > On Thu, Sep 15, 2022 at 05:23:10PM +0200, Volker Wysk wrote:
> > > I've lately set up the Haskell environment on my Linux box, with no
> > > problems. Then I have installed some packages with "cabal install", again
> > > without problems. But now I'm trying to install another package and I get a
> > > dependency conflict. It doesn't seem to matter which package I try to
> > > install:
> > 
> > This is quite weird, because neither directory nor ghc are
> > dependencies of rfc5051.
> > 
> > As a first step, can you try the following and report back whether you
> > successfully get to a GHCi a prompt?
> > 
> > $ cabal repl -z --build-depends rfc5051
> 
> This results in:
> 
> 
> desktop ~ $ cabal repl -z --build-depends rfc5051
> Resolving dependencies...
> Build profile: -w ghc-8.8.4 -O1
> In order, the following will be built (use -v for more details):
>  - rfc5051-0.2 (lib) (requires download & build)
>  - fake-package-0 (lib) (first run)
> Downloading  rfc5051-0.2
> Downloaded   rfc5051-0.2
> Starting     rfc5051-0.2 (lib)
> Building     rfc5051-0.2 (lib)
> Installing   rfc5051-0.2 (lib)
> Completed    rfc5051-0.2 (lib)
> Configuring library for fake-package-0..
> Preprocessing library for fake-package-0..
> Warning: No exposed modules
> GHCi, version 8.8.4: https://www.haskell.org/ghc/  :? for help
> Loaded GHCi configuration from /tmp/cabal-repl.-17863/setcwd.ghci
> Prelude> 
> 
> 
> Looks good, doesn't it..?

Yes, so this means that the problem is indeed the
~/.ghc/x86_64-linux-8.8.4/environments/default that Mikolaj predicted
and you confirmed in a sibling thread.

I'm not sure what the suggested fix is.  I find this part of the cabal
command line API extremely inscrutable.

Tom