I tried a problem I was looking at recently, to refactor a small rust crate to use one datatype instead of an enum, to help me understand the code better. I found o1-mini made a decent attempt, but couldn't provide error free code. o1-preview was able to provide code that compiled and passed all but the test that is expected to fail, given the change I asked it to make.

This is the prompt I gave:

simplify this rust library by removing the different sized enums and only using the U8 size. For example MasksByByte is an enum, change it to be an alias for the U8 datatype. Also the u256 datatype isn't required, we only want U8, so remove all references to U256 as well.

The original crate is trie-hard [1][2] and I forked it and put the models attempts in the fork [3]. I also quickly wrote it up at [4]

[1] https://blog.cloudflare.com/pingora-saving-compute-1-percent...

[2] https://github.com/cloudflare/trie-hard

[3] https://github.com/kpm/trie-hard-simple/tree/main/attempts

[4] https://blog.reyem.dev/post/refactoring_rust_with_chatgpt-o1...