Pretty neat stuff. Looks like the move generator is missing a few features like underpromotion but it is very concise. I wrote a rudimentary engine + move generator[1] using bitboards[2] a couple of years ago. Unfortunately python poorly suited for bitmath optimizations because it doesn't support fixed width integers. Once I saw how slow my movegen went compared to a c version, I gave up on finishing up the minimax search to complete the engine. It does run quite a bit faster in pypy but still no easy way to force 64 bit integers.

[1] https://github.com/vishvananda/ivory [2] https://chessprogramming.wikispaces.com/Bitboards