[Haskell-cafe] ANN: TernaryTrees- - An efficient ternary tree implementation of Sets and Maps

Don Stewart dons at galois.com
Thu Jul 2 19:45:47 EDT 2009

> Alex Mason wrote:
>> TernaryTrees is a package that extends Data.Set ad Data.Map with some  
>> ternary tree structures, based on the article  
>> [http://www.pcplus.co.uk/node/3074/] .
> For the string (or rather ByteString) version:
> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-trie
> Which has a number of other significant performance improvements (e.g.  
> node fusion, ByteString instead of String) and a highly expressive  
> interface. Because it uses ByteStrings it can trie any type which can be  
> serialized into a vector of bits[1], albeit indirectly.
> The real trick with tries is not in just having them[2], it's in having  
> the right interface to make use of what they're good at. For example, if  
> I have multiple tries, I'd like to merge them without doing it element  
> by element[3]. Or if I know I'm going to be making a number of similar  
> queries, it'd be nice if I could cache my position in the trie[4] to  
> avoid repeating the work for the prefixes of all my queries[5]. Using  
> tricks like these leads to significant improvements over using them like  
> hashtables; tries aren't hashtables just like lists aren't arrays.

Do you have benchmarks?

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