> Types marked with `#[must_use]` in Rust are pretty close to linear types. But must_use is a lint rather than being integrated with the type system.
An other issue with must_use is that it just requires use not “consumption” of the value, so if, say, you print it the lint is satisfied. Meaning it’s an issue for resources you’d want to be linear e.g. resources which really should be explicitly terminated because the termination can fail.
I don't know if GHC provides either, but either a borrowing or a dup feature would handle that (the latter would probably count as "cheat"). There may be other ways as well.
Since linear types are a separate opt-in feature you'd probably need (as far as I understand) you'd need separate printers anyway, so you could probably "cheat" them in. Though I think the sort of structures you'd want to be linear would generally not be amenable to print-debugging anyway.
An other issue with must_use is that it just requires use not “consumption” of the value, so if, say, you print it the lint is satisfied. Meaning it’s an issue for resources you’d want to be linear e.g. resources which really should be explicitly terminated because the termination can fail.