On Saturday, 25 February 2017 at 14:32:00 UTC, Ilya Yaroshenko
HyperLogLog++ is advanced cardinality estimation algorithm with
normal and compressed sparse representations. It can be used to
estimate approximate number of unique elements in an unordered
hll-d [1, 2] is written in D. It can be used as betterC library
without linking with DRuntime. hll-d has C header and C example.
Its implementation is based on Mir Algorithm 
1. mir.ndslice.topology.bitpack is used for arrays composed
of packed 6bit integers
2. mir.ndslice.sorting.sort is used for betterC sorting.
 Git: https://github.com/tamediadigital/hll-d
 Dub: http://code.dlang.org/packages/hll-d
 Mir Algorithm: https://github.com/libmir/mir-algorithm
hope more betterC lib.