13-OCT-2024

2322 - movegen-v2

A great culling has occurred as I move things towards the unified Square approach to notation. I’ve more or less got everything lined up, and am just chasing out bugs from the various bits that I tweaked incorrectly to return to compiling. At time of writing, six failing tests remain.

The approach I took seems alright, though it was tricky in spots. Essentially I have everything rely on an implementor of SquareNotation, which requires the implementor be capable of converting to a Square, which is a simple newtype around usize that constrains to 0..64 and provides some convenient const-time functions for working with it. The trait wraps and provides those functions for general use, eventually it would be nice to push as much to const-time evaluation as possible.

This should make it easy to have alternative implementations I can experiment with if I find better represnetaitons later, and should smooth the cutover should the need arise.

After getting Square setup throughout, I plan to do the same thing with Move, building my current, compact Move representation into the ‘Default’ MoveNotation implementation, similar to SquareNotation and Square. Also FEN needs to be factoryed in throughout. Here it will be much more likely that thr trait will be valuable, as there are lots of different move representation schemes, so by implementing the trait, I can set up a canonical pipeline to convert between different representations. Something like:

pub fn convert<M, N>(m: M) -> N where M: MoveNotation, N: MoveNotation {
    let i = Move::from<m>;
    N::from(i)
}

I don’t think it’s possible to write the more general:

impl<M, N> From<N> for M where M: MoveNotation, N: MoveNotation {
    fn from(n: N) -> M {
        let i = Move::from(n);
        M::from(i)
    }
}

because of orphan instances, but I think the first is good enough for now. I can always add more implementations later, and within hazel, it’s most likely that I’ll want to move to Move anyway.

Lots of gruntwork to do, but I think the result will be worth it.