Simon,
I think this is an important issue and I am willing to help and participate.
The issues for such a system are I believe more complex than is immediately apparent, and some of the early responses indicate that the complexity of the issue may not be well understood.
I would recommend a more incremental approach with more limited initial goals. Specifically, with X meaning to be determined:
1. A Haskell library is distributed in X format
2. After downloading, a Haskell library is built using procedure X. All libraries are built using the same sequence. Preferably the sequence is the same for the three compilers, and the build process is smart enough to determine which compiler is available, and adjust accordingly. There should be a build time option to override the automatic compiler choice.
3. A Haskell library is installed into directory (tree?) X. Again, preferably compiler independent, if practical.
4. A Haskell library includes, at a minimum, documentation X in format Y. This is the least interesting (at least to many developers :) ), but the _most_ important, requirement.
On Tue, 22 Apr 2003 15:00:39 +0100
"Simon Peyton-Jones"
Gentle Haskellers
Haskell has now got a decent, hierarchical module system, supported by GHC, Hugs and NHC, and the library structure is now quite well populated. For example, here are the "base" libraries shipped with GHC (similar libraries come with Hugs and Nhc): http://www.haskell.org/ghc/docs/latest/html/base/index.html
Languages flourish when libraries are plentiful, reliable, and well documented. In an open-source community like the Haskell community, plentiful libraries depend on contributions from the community.
The difficulty is that it is currently not obvious what Joe Programmer should do to contribute a library to the community.
I think this difficulty is a major obstacle to Haskell's progress, perhaps even the largest single obstacle today.
One route to getting a library widely distributed is to get it into the "libraries" source tree used by GHC, Hugs, and NHC. That has the merit that the library will be distributed with each of these compilers. But it's too much of a "cathedral" approach. There is no way to distribute libraries between releases, and it makes the distributions ever larger and more complex for the GHC/Hugs/Nhc teams to build.
To complement this, there ought to be an easy "bazaar" way for Joe Programmer to implement a library, build distributions, put them up on his web site for others to download, and add a link to some central library index so that people can find it. Sadly this is not an entirely simple task, because (a) the library should work on all Haskell implementations, and (b) should be packaged for binary installation on a variety of platforms (Windows, Linux, OpenBSD, Mac etc). Indeed, since GHC, Hugs and Nhc have different packaging mechanisms, there's a kind of (a)*(b) product involved. The bottom line is that today the obstacles are high enough to discourage all but the most motivated.
What is needed is some kind of software infrastructure to automate the common tasks, and to give clear instructions about the non-automatable parts. This infrastructure should not be part of the (complicated) GHC (or Hugs, or Nhc) build systems; indeed, while it will certainly contain implementation-specific parts, its structure should be implementation independent. Simon Marlow emitted a message a while ago about this, but discussion petered out:
http://www.haskell.org/pipermail/glasgow-haskell-users/2002-November/thr ead.html#4322
The lack of this library-building infrastructure is a serious problem. Solving it, or even partially solving it, would be a huge step forward. So this message is really to try to kick-start the process again. Is anyone willing to invest effort in making this happen?
It's probably a task that is too big for one person. I think what we need is
A library-infrastructure Czar, who will a) do the core design and implementation b) coordinate the whole thing to make sure progress happens
A bunch of library-infrastructure Supporters, who are willing a) to contribute thoughtfully to the design b) to implement pieces of it, for example pieces specific to one implementation (e.g. GHC) or one target architecture (e.g. PowerPC)
Perhaps the first thing to do is to assemble list of people who would be willing to contribute as supporters (in the above sense), hoping that a Czar may then emerge by popular acclaim. Would you like to reply, perhaps to the 'libraries@haskell.org' list, so indicate interest.
I really think this is important. If we do not collectively evolve a way to develop libraries in "bazaar" mode, I think Haskell will at best develop more slowly, and at worst wither away.
Simon
PS1: This is all distinct from the question of library *content* --- that is, what the module name, discussion about the signature of the exported types and functions are --- which does seem be handled OK by the 'libraries' list. This message concerns library-building *infrastructure*.
PS2: Another entirely-orthogonal question is where library source code *lives*. One possibility is to use the same CVS repository that GHC/Hugs/Nhc use for libraries, albeit in a separate subtree. Perhaps fptools/user-libs/joe-bloggs/*. Another possibility is SourceForge. Finding backed-up CVS space for source code is not a problem.
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