Slim is collection of surprisingly space efficient data types, with corresponding serialisation APIs to persisting them on-disk or for transport.<p>Why slim<p>As data on internet keeps increasing exponentially, the capacity gap between memory and disk becomes greater.<p>Most of the time, a data itself does not need to be loaded into expensive main memory. Only the much more important information, WHERE-A-DATA-IS, deserve a seat in main memory.<p>This is what slim does, keeps as little information as possible in main memory, as a minimised index of huge amount external data.