[meuk]

This is cool. I wanted to comment on the necessity of knowing the approximate size of N a priori, but this is very clearly stated on the github page.

Interesting alternatives that also support insertion, deletion, and lookup (is there a name for this interface?) are AVL trees and hash tables.

As described in https://arxiv.org/pdf/1711.00275.pdf, tiered vectors can be improved further:

"We present a highly optimized implementation of tiered vectors, a data structure for maintaining a sequence of n elements supporting access in time O(1) and insertion and deletion in time O(n^ε) for ε > 0 while using o(n) extra space."

[igushev]

It seems I need to add automatic restructuring to the structure, so it would maintain perfect lengths of DEQs