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

Ivan Miljenovic ivan.miljenovic at gmail.com
Fri Jun 25 00:58:18 EDT 2010

On 25 June 2010 14:41, David Menendez <dave at zednenem.com> wrote:
> On Thu, Jun 24, 2010 at 3:08 AM, Ivan Miljenovic
> <ivan.miljenovic at gmail.com> 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 at gmail.com

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