On Thu, Feb 19, 2009 at 9:51 PM, Eugene Kirpichov
Greetings,
Is there a typeclass for mappings with a Data.Map-like interface, with stuff like: empty, insert, insertWithKey, unionWith etc. ? And, probably, a similar typeclass for mutable mappings like Data.Hashtable.
Looks like such a thing would be useful; as for now, I see at least two applications: Data.Map and Data.Trie (bytestring-trie) - it's a pity that they have rather similar interfaces, but the latter lacks many methods and some are named in a different way. Also, Data.Map has some inconsistensies, too: for instance, it has an insertWith' but lacks a unionWith'. "One typeclass for all" would eliminate these inconsistencies.
I'm asking mainly because I've been wondering why noone has yet written a mutable hashtable package with a MArray-like interface, I wrote a small thing myself and I am unsure as to what interface it should have.
Probably not adding anything terribly useful to this except to say that it'd be useful to me too - I've written a binding to a perfect hashing library (PerfectHash on hackage) which implements only 'fromList' and 'lookup', so a slightly more fine-grained type class hierarchy would be nice. (This particular implementation is useful when you have a lot of keys, but all known at run-time.) Mark -- A UNIX signature isn't a return address, it's the ASCII equivalent of a black velvet clown painting. It's a rectangle of carets surrounding a quote from a literary giant of weeniedom like Heinlein or Dr. Who. -- Chris Maeda