[Haskell-cafe] Cabal problem, broken packages?

[Volker Wysk]

Am Donnerstag, dem 15.09.2022 um 17:17 +0100 schrieb 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.

For reference, here's the beginning of that file again:


clear-package-db
global-package-db
package-db /home/v/.cabal/store/ghc-8.8.4/package.db
package-id ghc-8.8.4
package-id bytestring-0.10.10.1
package-id unix-2.7.3-
f9e049162269c42fac796ce2193bc96fb95dfe3ac975de03338213cf0e37a14a
package-id base-4.13.0.0
...


What makes me wonder is, that some but not all "package-id" entries have a
large hexadecimal string at the end of the line...

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

Bye
Volker