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

[Badi' Abdul-Wahid]

Just my two cents: Nix is great, Modules is not perfect, but it is good.

I think that Nix solves a lot of the problems, but will likely take a while
to be adopted.
I'm still exploring Nix and NixOS, but I have to say: I really like it.

I've found that a practical solution for my own development work has been
the modules project [1].
I'd describe it as a happy medium between manual software management and
Nix.
The upside is similar to that of Nix: software with conflicting
dependencies can coexist.
The downside is that there is no package management: everything needs to be
installed manually and configured with --prefix.

However, I've found that the advantages far outweigh the disadvantages.
For instance, tracking down a bug where software A which depends on B which
depends on C, but C1 conflicts with C2, C3... etc, and you need to test all
permutations.
In my case, package C was multiple versions of cuda: 3.2, 4.0, 4.1, and 5.0
Testing was, eg:
$ module load environment/A-1.0/B-2.0/cuda-4.0
$ ./runtest.sh

I'd really like to see if cabal is compatible with this setup. Hopefully
I'll have time in the next few weeks to look into it.

Quick example of a module file for gsl on my machine:
$ cat ~/privatemodules/gsl/1.15
#%Module

set name    gsl
set version 1.15
set prefix  /opt
set root    $prefix/$name/$version

prepend-path PATH              $root/bin
prepend-path INCLUDE           $root/include
prepend-path LD_LIBRARY_PATH   $root/lib
prepend-path DYLD_LIBRARY_PATH $root/lib


[1] http://modules.sourceforge.net/



On Thu, Dec 13, 2012 at 1:12 AM, Rustom Mody <rustompmody at gmail.com> wrote:

> On Thu, Dec 13, 2012 at 1:29 AM, Brandon Allbery <allbery.b at gmail.com>wrote:
>
>> On Wed, Dec 12, 2012 at 12:51 PM, Andre Cunha <andrecunha.usp at gmail.com>wrote:
>>
>>> Janek, did you mean something like Rubygems (http://rubygems.org)? It
>>> manages the download, installation and manipulation of Ruby packages,
>>> called "gems". A gem can contain executable programs or libraries (just
>>> like traditional packages, like .rpm). Rubygems also handles dependencies
>>> between gems, and allows you to update them.
>>>
>>
>> But doesn't solve the actual problem;
>>
>
> Considering that this question is such a FAQ, I believe it would be
> worthwhile discussing  what we think the 'actual problem' is.
>
> When Algol-60 was being implemented, the challenge was how to compile
> using only 2000 words of memory (or something as ridiculous as that). The
> solution was to make a compiler with 20-odd passes.
> [Sorry if the details are wrong; its from (neurological) memory]
>
> Today not just compilers but databases are vying with each other to go
> back from disk to memory -- hardly surprising considering that a vanilla
> machine bought today has a TB of disk and GBs of memory.
>
> In short the goal-posts shift with time and we need to readjust priorities
> accordingly.
>
> For myself if the total disk usage of my haskell-related installation were
> to go up from being linear in the number of packages to quadratic, I am
> unlikely to care.  Of course total naivete in package-management strategy
> may make it exponential which would make me sit up!
>
> Reminds me of a restatement/corollary to Moore's law I recently saw:
> Programmers' cost increase exponentially with time.
>
> Just alpha-rename 'programmer' to 'cabal-installer'
>
>
>
> On Thu, Dec 13, 2012 at 12:19 AM, Ertugrul Söylemez <es at ertes.de> wrote:
>
>> I'm afraid the burden is that you would have to write the necessary Nix
>> expressions for your Haskell packages, so until we create a real Nix
>> channel for Hackage the barrier to entry is high.  But it's certainly
>> possible as a community project.
>>
>>
> I believe you are saying something significant here. Here's my rendering
> of it.
>
> Currently we have a 'managed' hackage server talking to an unmanaged cabal
> client (in the sense of
> http://ivanmiljenovic.wordpress.com/2010/03/15/repeat-after-me-cabal-is-not-a-package-manager
> /  )
>
> We need to move to hackage talking to a managed (as with nix) client.
>
> So what work is needed to make this happen?
>
> --
> http://www.the-magus.in
> http://blog.languager.org
>
>
>
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>


-- 

Badi' Abdul-Wahid
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