[Haskell-cafe] Cabal hell

[Alexey Shmalko]

I really love Qt versioning scheme when applied to compatibility [1].

Given version is Major.Minor.Patch:

Major releases may break backwards binary and source compatibility,
although source compatibility may be maintained.
Minor releases are backwards binary and source compatible.
Patch releases are both backwards and forwards binary and source compatible.

So that you know your package will work with any Qt version that has the
same major version and minor version is greater-equal to the one you
developed your package with. It would be really great if everyone followed
this scheme.

As a drawback I can note that this requires strict discipline from a
library developer. It's also harder to get binary compatibility right for
Haskell because of cross-module optimization GHC does.

[1] https://wiki.qt.io/Qt-Version-Compatibility

On Thu, Apr 9, 2015 at 7:44 PM, Patrick Redmond <plredmond at gmail.com> wrote:

> Since learning Haskell I've had the pleasure of finding my way out of a
> cabal hell or two. I've developed some knowledge to cope with it [1], but
> mostly concluded that if I can avoid burdening my projects
> with dependencies that have many of their own dependencies, then cabal hell
> can be averted. This puts somewhat of a damper on the joy of haskell's
> composability.
>
> With the new release of GHC I've observed a flurry of discussion on
> haskell mailing lists and from Linux distro maintainers about all the
> fixing and patching required to keep the haskell ecosystem going.
>
> Meanwhile I've learned other languages and used other tools that don't
> seem to have this problem that haskell does. For example, in the elm-lang
> community the package management tool enforces strict api-versioning, and
> in the clojure ecosystem people talk about "repeatability" and achieve it
> by using mostly exact-version requirements, even including the language
> (the language version is a dependency of a project, rather than a
> constraint of the environment).
>
> I guess I'm wondering why we don't try something simpler to solve the
> haskell cabal hell problem. How about using minimum version dependencies
> only, not ranges, since we can't accurately guess about the future
> compatibility of our projects. How about automatic api-versioning of our
> projects to give the version numbers some rigid semantics with regard to
> package compatibility?
>
> [1] http://f06code.com/post/90205977959/cabal-usage-notes
>
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