This is a Haskell implementation of the Datar-Gionis-Indyk-Motwani algorithm for approximately counting occurences of certain elements in a (very large) prefix of a (possibly infinite) stream.
This package is now available on Hackage with the name dgim:
cabal install dgim
or by name in your .cabal file. However, it is in the alpha stage and the API is likely to change in the future.
Install cabalg, if you do not already have it with cabal install cabalg.
cabalg https://github.com/musically-ut/haskell-dgim