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

Johan Tibell johan.tibell at gmail.com
Sun Feb 20 02:18:50 CET 2011

On Sat, Feb 19, 2011 at 4:49 PM, wren ng thornton <wren at freegeek.org> wrote:
> How does, or will, this package differ from Milan Straka's
> http://hackage.haskell.org/package/hashmap ?

It's a continuation of that work. The unordered-containers
implementation is more space efficient and a bit faster. Milan also
uses a Patricia trie in his implementation. I plan to switch to a
hash-array mapped trie (HAMT) in the future. It's about 25% faster for
lookups but at the moment quite a bit slower for inserts. Once we got
some new faster array copy primops in GHC we can hopefully improve the
insert time a lot. A HAMT also has much lower space overhead per


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