Re: [Haskell-cafe] Cabal problem, broken packages?

The problem with the old way of doing things is exactly what you're seeing: conflicting package versions that interfere with each other. Cabal and stack both know how to expose only the package versions needed by a build, while retaining all versions needed by various build environments. On Thu, Sep 15, 2022 at 12:39 PM Volker Wysk wrote:

Am Donnerstag, dem 15.09.2022 um 12:25 -0400 schrieb Brandon Allbery:

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It looks good because you're using it the way you're supposed to instead of blindly using --lib to install things. That creates dependency issues like what you're having. Basically, don't use --lib unless you know what you're doing.

Remove the environment file, and create projects with dependencies on the libraries you want, instead of trying to preinstall them. Cabal knows how to manage packages for you so they don't conflict.

I admit that I don't really know what I'm doing, when using cabal. I've built my projects by calling ghc from a generic Makefile for a long time now. And you're saying I should build them with "cabal build" instead? This would mean that I must change my long-fostered build environment.

Looks like I have to do some reading.

Bye, Volker

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On Thu, Sep 15, 2022 at 12:12 PM Volker Wysk wrote:

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Am Donnerstag, dem 15.09.2022 um 16:31 +0100 schrieb Tom Ellis:

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On Thu, Sep 15, 2022 at 05:23:10PM +0200, Volker Wysk wrote:

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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..?

Volker _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.

-- brandon s allbery kf8nh allbery.b@gmail.com