A while ago I wrote a little data structure that allows weighted random selection-without-replacement from a collection of values in O(log n) time.[1] I'm now in the process of packaging it up for Hackage, but I'm looking for good names for both the type and its operations. The name I have at the moment is "Pool", which I'm reasonably happy with, but I wanted to see if I could find anything better. Asking on #haskell got me a few responses: * Hat (cute, but conflicts with the program tracer) * Bag (already way too overloaded) * Bucket (not as suggestive as Pool) I have three main operations: * "pull" selects a random element, returning it and the remainder, but fails if the pool is empty * "pullN" selects /n/ distinct elements, returning them and the remainder, but fails if the pool has too few elements * "takeN" selects up to /n/ distinct elements, returning them and the remainder, but returns no more elements than could be found in the pool (analogous to Data.List.take) Any suggestions? Stuart [1] Actually I delegated most of the work to the data-structure-in-a-can that is Data.FingerTree, but that's another story.