I'm pleased to announce the fruits of my labours during AusHac [1]: version 0.0.0.0 of the container-classes library [2] I was talking about in my last blog post [3]. [1]: http://www.haskell.org/haskellwiki/AusHac2010 [2]: http://hackage.haskell.org/package/container-classes [3]: http://ivanmiljenovic.wordpress.com/2010/07/14/data-oriented-hierarchies/ The purposes of this library is two-fold: * As a library writer, let your users choose which data structure they want to use rather than whichever one you decided upon when writing the library (e.g. you use lists predominantly, but your users may want to use Sets; by outputting a generic Container value yoru users don't need to keep using Set.fromList and Set.toList). * When writing your own code and you realise that you're using the wrong data structure for your purposes, if you used this library (correctly) then the amount of work you need to do to swap data structures is minimised. This current version is only a first draft. As such, I would appreciate feedback on the API. Currently, it provides its own definitions of all list-oriented functions in the Prelude plus a few more (e.g. partition), and list instances of all the classes. In terms of definitions, most class methods have default definitions in terms of fold. Furthermore, as much as possible I've defined them using a build/fold setup outlined in the paper "A Short Cut to Deforestation" by Andrew Gill, John Launchbury and Simon Peyton Jones (however I haven't yet defined the rules to get this used yet). However, the current list instances use the pre-defined versions in the Prelude and Data.List; I'm not sure if I should keep it this way or - where equivalent - use the pre-defined ones so that hopefully conversions from lists to other data types would also be removed without needing intermediary data structures. I also plan on adding more instances and a Lookup class for Maps, etc. However, we have to start packing up the room now and so my hacking is at an end for this weekend :( -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com