[bodhi]

> As far as I can see, you need to use `Box`

Which is exactly what you said in the first place!

> So you can have a list of Box<Show> in Rust, but you can't have a list of Show in Haskell.

But isn't this comparing two different things? You can't have a list of trait/typeclass in either language (excuse the pseudo-syntax):

    Rust: [Bar]
    Haskell: [Bar a => a]

But you can (with some extensions in Haskell) have:

    Rust: [Box<Bar>]
    Haskell: [Box Bar]