often i try to implement an append-only random-access data structure. it's a fun puzzle for my confused mind. i never finish it, but today i thought about it a little bit and i think over the years i might be able to put together a simplified form and maybe make it exist some day. here is where i wrote right now. i started spinning out when I renamed Simple.Write to Simple.RangedData . I was in the middle of implementing a leaf iterator, so as to make a simple way to count the number of data leaves and associate them with a depth. the approach, as written in the file, is to simply relink to leaves with excessive depth each flush, so as to maintain O(log n) random seek time. i vaguely recall that approach has a major issue, but i might be remembering wrongly, and it's still quite exciting to be able to spend some minutes trying.