Method meet

examples/parametrized_function.rs:38–55

(lhs: Partial<Self>, rhs: Partial<Self>)

    }

    fn meet(lhs: Partial<Self>, rhs: Partial<Self>) -> Result<Partial<Self>, Self::Err> {
        use Variant::*;
        assert_eq!(lhs.least_arity, 0, "spurious child");
        assert_eq!(rhs.least_arity, 0, "spurious child");
        let variant = match (lhs.variant, rhs.variant) {
            (Any, other) | (other, Any) => Ok(other),
            (Integer(l), Integer(r)) => Ok(Integer(max(r, l))),
            (Fixed(li, lf), Fixed(ri, rf)) => Ok(Fixed(max(li, ri), max(lf, rf))),
            (Fixed(i, f), Integer(u)) | (Integer(u), Fixed(i, f)) if f == 0 => Ok(Integer(max(i, u))),
            (Fixed(i, f), Integer(u)) | (Integer(u), Fixed(i, f)) => Ok(Fixed(max(i, u), f)),
            (Bool, Bool) => Ok(Bool),
            (Bool, _) | (_, Bool) => Err("bool can only be combined with bool"),
            (Numeric, Integer(w)) | (Integer(w), Numeric) => Ok(Integer(w)),
            (Numeric, Fixed(i, f)) | (Fixed(i, f), Numeric) => Ok(Fixed(i, f)),
            (Numeric, Numeric) => Ok(Numeric),
        }?;
        Ok(Partial { variant, least_arity: 0 })
    }

    fn arity(&self) -> Arity {
        Arity::Fixed(0)