Any libraries for dictionary coding (compression) of array structures ?

[cblake]

Since gzip is lz77 + huffman coding and lz77 is basically a [sliding window 
dictionary coder](https://en.wikipedia.org/wiki/LZ77_and_LZ78), and since zippy 
is a pure Nim re-write of gzip algos, you might be able to extract/adapt 
relevant parts of <https://github.com/guzba/zippy>. I'm not sure it's the 
easiest path, but it seemed worth mentioning.