[Haskell-cafe] Can cabal be turned into a package manager?

[Ertugrul Söylemez]

"Janek S." <fremenzone at poczta.onet.pl> wrote:

> In the recent months there was a lot of dicussion about cabal,
> dependency hell and alike. After reading some of these discussions
> there is a question I just have to ask:
>
> Why not create a package manager (like rpm or apt) for Haskell
> software?

There is no need to reinvent that.  See below.


> I've been using Linux for years. Software for Linux is mostly written
> in C and C++. There are thousands of libraries with lots of
> dependencies and yet: a) Linux distributions manage to have package
> repositories that are kept in a consistent state b) Linux package
> managers can avoid dependency hell, automatically update to new
> packages, etc. Linux people did it! Is there any technical issue that
> prevents Haskell people from doing exactly the same thing? Or are we
> just having non-technical problems like lack of money or developers?

Actually Linux distributions do all the hard work for you.  Package
maintainers know what I'm talking about.  It's a difficult task to
specify correct dependencies, tedious to negotiate with all the other
developers and all in all provide a consistent system.  But that's only
half of the story.

The problem starts with the File Hierarchy Standard (FHS), which
essentially doesn't allow you to employ a more useful concept.  That's
why an experimental (yet quite usable) Linux distribution called NixOS
[1] has established.  It recognizes the problems of the FHS.  The
solution is simple and radical:  the FHS sucks, so ignore it.

NixOS uses the Nix package manager, which you can also use for your
Haskell packages to escape from the dependency hell.  With Nix you can
even allow all users to install arbitrary packages without interfering
with other users, even the same packages with different versions.  Two
programs can depend on different versions of the same library, etc.
It's the package manager of the future.  Unfortunately the concept is
new and different enough that it will be difficult to convince a large
portion of the Linux community to employ it.  It's the same issue
Haskell has in the programming language world.

There is no need to switch to NixOS to use Nix.  You can even install it
in your home directory.

[1]: http://nixos.org/


Greets,
Ertugrul

-- 
Not to be or to be and (not to be or to be and (not to be or to be and
(not to be or to be and ... that is the list monad.
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