[clean-list] discussing issues of uniqueness typing
Wolfgang Jeltsch
wolfgang at jeltsch.net
Tue Jun 28 16:50:01 MEST 2005
Am Dienstag, 28. Juni 2005 09:03 schrieben Sie:
> Dear Wolfgang,
>
> First of all, in our system uniqueness does not always imply unique
> references: If a function delivers a unique result, this means that
> evaluating such a function will not increase the number of references to
> the closure.
Dear Sjaak,
do you think of situations like
let x = fwritec char file in (x,x)
where x is referenced multiple times? Are there other situations in which a
closure marked as unique can be referenced more than once?
> Your remark concerning the subtyping relation
>
> t1 ->x t2 <= t1 ->* t2
>
> is right: it can be allowed. At the time we implemented the uniqueness type
> system we did not see the advantages of having this relation. But, for
> orthogonally reasons, it would have been better to allow it.
Ah, that's good. Currently, I write my diploma thesis (similar to master's
thesis) where I deal with different approaches for integrating functional and
imperative programming concepts. I'd like to allow the above subtype
relation in my presentation of uniqueness typing if that's possible because I
don't want to have unnecessary restrictions in the type system.
> Regards,
>
> Sjaak
Best wishes,
Wolfgang
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