Another common usage for Map is as a functional integer-indexed
random access array.
Once I implemented the standard algorithm for random shuffle
of a list using Data.Map Int. It was much nicer than the STArray
version, in my opinion. But when I tried switching to Data.IntMap,
hoping to make it faster, I was devastatingly disappointed. Now
I understand why.

�

A couple thoughts:

If you're going to provide an isSingleton method, provide�

getSingleton :: IntMap m -> Maybe (Int, a)

which is trivial based on the current implementation.

For my TrieMap package, I've been working on my WordMap implementation here. �(Using Words as keys makes my life easier, and it doesn't take too much work to write a wrapper that provides an order-preserving bijection from Int to Word.) �It provides O(1) size, but its design reflects my willingness to trade memory and code size for speed. ;)

Louis Wasserman
wasserman.louis@gmail.com
http://profiles.google.com/wasserman.louis