Proposed FHDL in Rust

alu.rs

struct Alu {
    pub sel: Signal,
    pub a: Signal,
    pub b: Signal,
    pub o: Signal,
    pub co: Signal,
}

impl Alu {
    #[fhdl]
    pub fn new(width: u16) -> Self {
        Alu {
            sel: signal!(2),
            a: signal!(width),
            b: signal!(width),
            o: signal!(width),
            co: signal!(),
        }
    }

    #[fhdl]
    pub fn fragment(&self) {
        #[comb]
        if self.sel == 0x0 {
            self.o = self.a | self.b
        } else if self.sel == 0x1 {
            self.o = self.a & self.b
        } else if self.sel == 0x2 {
            self.o = self.a ^ self.b
        } else {
            cat!(self.o, self.co) = self.a - self.b
        }
    }
}