Re: [Haskell-cafe] ANN: unordered-containers - a new, faster hashing-based containers library

On Wed, Feb 23, 2011 at 12:57 PM, Gwern Branwen wrote:

On Wed, Feb 23, 2011 at 12:45 AM, Max Bolingbroke wrote:

...

I'm a bit sceptical that it is (I was not convinced by the earlier strict-set-inclusion argument, since that's another Data.Map feature I've never used). I thought of some other possibilities though:  1. If copying an unordered-collection to a flat array you can improve the constant factors (not the asymptotics) with O(1) size to pre-allocate the array

For kicks, I grepped my local repos for users of Data.Set's size function. My results are imperfect (I have few Github repos, I didn't check .lhs files, I only grepped files for 'Set.size' or 'S.size'), but I found around 100 uses of Data.Set.size.

Could you manually look at some of them to see if you find something interesting. In particular `Set.size s == 0` (a common use of size in imperative languages) could be replaced by `Set.null s`. Johan