[plt-scheme] require/typed and polymorphic signatures

From: Robby Findler (robby at cs.uchicago.edu)
Date: Sun Jul 13 21:41:40 EDT 2008

I consider this feasible but, at the moment, the contract library
doesn't support it. There are some technical issues that I think I
have to compromise on, but I've decided I'm willing to do that... so I
hope to add this before too long. I'm not sure if there are type-level
issues, tho.


On Sun, Jul 13, 2008 at 8:35 PM, John Nowak <john at johnnowak.com> wrote:
> I recently attempted to dive into Typed Scheme. Unfortunately, a few things
> have stopped me from using it. The major issue is that it seems impossible
> to import procedures with polymorphic signatures. For example, I'd like to
> do this:
>  (require/typed
>    srfi/1
>    (fold (All (a b) ((a b -> b) b (Listof a) -> b))))
> Unfortunately, this fails because Typed Scheme is unable to generate an
> appropriate contract. Am I correct in thinking that such a require statement
> is current impossible? If so, might this be remedied in a future version?
> I'm aware this may not be considered feasible.
> - John
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