Example worker FSM in rust

main.rs

mod worker;

use worker::Worker;

fn main() {
    let worker = Worker::new()
        .initialize()
        .do_work()
        .reset();
    println!("{:?}", worker);
}

worker.rs

#[derive(Debug)]
pub struct Worker<S> {
    progress: Option<bool>,
    state: S,
}

#[derive(Debug)]
struct Waiting;

impl Worker<Waiting> {
    pub fn new() -> Self {
        Worker {
            progress: None,
            state: Waiting,
        }
    }

    pub fn initialize(self) -> Worker<Working> {
        println!("{:?} - Initializing", self);

        Worker {
            progress: Some(false),
            state: Working,
        }
    }
}

#[derive(Debug)]
struct Working;

impl Worker<Working> {
    pub fn do_work(self) -> Worker<Finished> {
        println!("{:?} - Doing work", self);

        Worker {
            progress: Some(true),
            state: Finished,
        }
    }
}

#[derive(Debug)]
struct Finished;

impl Worker<Finished> {
    pub fn reset(self) -> Worker<Waiting> {
        println!("{:?} - Resetting", self);

        Worker {
            progress: None,
            state: Waiting,
        }
    }
}