Id doesn´t have to create a copy of the original object ( I infer this from
referential transparency) so the new list must store the same original
reference. Any pure structure would conserve references after id. filter as
far as I know. Am I wrong?
2010/4/8 Dan Piponi
I have a situation where I have a bunch of lists and I'll frequently be making new lists from the old ones by applying map and filter. The map will be applying a function that's effectively the identity on most elements of the list, and filter will be using a function that usually gives True. This means that there is potential for a large amount of sharing between these lists that could be exploited, something that ordinary lists would do badly. Does anyone have a recommendation for a pure functional data structure for this case?
(It reminds me a bit of my own antidiagonal type, but that's not well adapted to the highly dynamic situation I'm describing.) -- Dan _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe