[Haskell-cafe] Re: Graph library, was: Haskell.org GSoC
benjovi at gmx.net
Thu Feb 12 09:42:16 EST 2009
Daniel Kraft schrieb:
> Don Stewart wrote:
>>> - Graphs.
>> True graphs (the data structure) are still a weak point! There's no
>> canonical graph library for Haskell.
> That sounds interesting... What do you mean by "no canonical" library?
> Are there already ones but just no "standard" one? But in this case, I
> don't think adding yet another one will help :D Or isn't there a "real"
> general graph library?
I would also like to see a project working on a new graph library.
Currently, there is at least Data.Graph (just one Module, package
containers), based on Array - adjacency lists, and the functional graph
library (package fgl).
I think a good general purpose graph library is tricky though:
- There are lot of variants of graphs (trees, bipartite, acyclic,
undirected, simple, edge labeled etc.), hard to find adequate and easy
to use abstraction.
- There is no single 'best' implementation (mutable vs. unmutable etc.).
- Its hard to find good traversal and zipper abstractions, though fgl
has some nice ones.
- The complexity of algorithms varies greatly depending on the
particular kind of graph.
Anyway, that's why it is challenging and interesting.
> If so, this would be a nice thing to do :) I could look at existing
> ones (like Boost's graphs) to get a feeling for how an interface might
> look like and what functionality to implement.
> BTW, is there some sort of "project hosting" specifically for such
> Haskell projects? Or should I go with sourceforge (for instance) for
> developing this, if I gave it a try?
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