Hydro DSL readability

[ydewit]

I am going over the Hydro DSL in order to understand it in more detail and how trait and generics are constraining the DSL by construction. I am wondering if a PR that uses where clauses where possible and that uses generic parameter names consistently would be acceptable with the goal of improving the readability.

What I have in mind is pretty straightforward:

This (an alternative could be Item, Loc, Bnd, Ord etc):

pub struct Stream<T, L, B, O = TotalOrder> {
    location: L,
    pub(crate) ir_node: RefCell<HydroNode>,

    _phantom: PhantomData<(T, L, B, O)>,
}

instead of:

pub struct Stream<T, L, B, Order = TotalOrder> {
    location: L,
    pub(crate) ir_node: RefCell<HydroNode>,

    _phantom: PhantomData<(T, L, B, O)>,
}

And:

    pub fn reduce_commutative<F: Fn(&mut T, T) + 'a>(self, comb: impl IntoQuotedMut<'a, F, L>) -> Optional<T, L, B>

instead of:

    pub fn reduce_commutative<F>(self, comb: impl IntoQuotedMut<'a, F, L>) -> Optional<T, L, B>
    where
        F: Fn(&mut T, T) + 'a,

[shadaj]

I like this idea! Indeed, pushing some of the constraints into where clauses makes things a lot more readable. If you'd like to make a PR with this refactor, would be happy to review it, otherwise I can take a stab soon.