boydjohnson / lin-rado-turing Goto Github PK

Here is the current signature of recurr_check:

fn recurr_check(
        &mut self,
        step: usize,
        snapshots: Option<&mut Snapshots<S, Sym>>,
        deviations: Option<&Vec<i64>>,
        init: usize,
        beeps: &Beeps<S>,
        dev: i64,
    ) -> Option<Halt>

snapshots and deviations are both Options that need to be
unwrapped in the function body. I think it would be cleaner to do that
unwrapping outside of the function body, and only call the function
once it's known that there really are snapshots and deviations to be
passed in. recurr_check is a complicated function, and saving some
indetation would make it easier to read.

In spirit this is along the lines of d7ad4f1. I would implement it
myself, but this change requires convincing the borrow checker, and I
really can't deal with the borrow checker.

An n-state k-color TM program has nk instructions. We've been separating these with single spaces. But this means that parsing is ambiguous. Is 1RB 1LB 1LA 0LC 1RH 1LD 1RD 0RA a 4-state 2-color program or is it 2-state 4-color? It's possible to guess, but it's still annoying.

To make parsing unambiguous, use one space to separate the colors within a state and two spaces to separate the states. The program above becomes 1RB 1LB 1LA 0LC 1RH 1LD 1RD 0RA as 4-2 and 1RB 1LB 1LA 0LC 1RH 1LD 1RD 0RA as 2-4. (This means that as strings, 4-2 programs are two characters longer than 2-4.)

I got this idea from the Ligocki repo: https://github.com/sligocki/busy-beaver