As Type::Tuple is becoming more actively used in implementations, I think we should implement Homogeneous Tuples before the refactoring cost becomes too high.

I’m considering an implementation like the following using an enum:

#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub enum TupleType<'db> {
    Heterogeneous(HeterogeneousTupleType<'db>),
    Homogeneous(HomogeneousTupleType<'db>),
}

#[salsa::interned]
pub struct HeterogeneousTupleType<'db> {
    elements: Box<[Type<'db>]>,
}

#[salsa::interned]
pub struct HomogeneousTupleType<'db> {
    element: Type<'db>,
}

Expected Issues

Currently, it seems that there is no way to assign a homogeneous tuple type in the tests.

Do you have any suggestions for a proper way to handle this? Or should we wait for another feature to be merged first?