Re: [Haskell-cafe] Fwd: signficant improvements to the containers package

On 25 June 2010 14:41, David Menendez wrote:

On Thu, Jun 24, 2010 at 3:08 AM, Ivan Miljenovic wrote:

...

As an aside, Alex Mason and I are discussing the possibility of taking advantage of AusHack *shameless plug* to write some kind of classes for the different types of containers with a hierarchy.  I know about ListLike, but there doesn't seem to be any applicable classes for generic containers (i.e. the abstract API of a Set; something like ListLike would then be an extension on it) and for lookup data structures (Map k a, [(k, a)], etc.).

Be sure to look into Okasaki's work on Edison. It has classes for sequences (list-like structures) and collections (sets, heaps) and associations (maps, priority queues) and a paper discussing the design decisions.

Yeah, we will be. The reason this came up: Thomas Berekneyi wanted to use such classes for the rewrite of FGL, and when he discussed it on #haskell people generally indicated that edison was the best out there but was a bit long in the tooth and something like it should be re-written (though no-one seemed to volunteer... hmmm... :p). For example: it's a little weird that edison re-exports Data.Set and uses it for the instance with a type alias (same with map, Seq, etc.) rather than just using Data.Set itself. I also find the structuralInvariant and instanceName fields to be a little odd, whereas strict can now be shifted off to DeepSeq (or whatever the class is called). -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com