[plt-scheme] require/typed and polymorphic signatures

That's the compromise. It will return #f instead of blowing up (like I
think it should). Many other primitives will blow up (car, function
application) but the predicates won't.

Robby

On Sun, Jul 13, 2008 at 9:58 PM, Matthias Felleisen
<matthias at ccs.neu.edu> wrote:
>
>
> How about the
>
>  (if (number? x)
>     ...
>     ...)
>
> issue when x has a Forall(X) type? We should do X - number? in the else
> branch, but this won't work for Robby's polymorphic contracts.
>
> -- Matthias
>
> On Jul 13, 2008, at 9:50 PM, Sam TH wrote:
>
>> On Sun, Jul 13, 2008 at 9:41 PM, Robby Findler <robby at cs.uchicago.edu>
>> wrote:
>>>
>>> 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.
>>
>> There aren't any type level issues, or at least not any that I know
>> about.  So using `require/typed' with polymorphic types is just
>> waiting for support from the contract library.
>>
>> Thanks,
>> sam th
>>
>>>
>>> Robby
>>>
>>> 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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>>>>
>>>>
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>>>
>>
>>
>>
>> --
>> sam th
>> samth at ccs.neu.edu
>> _________________________________________________
>>  For list-related administrative tasks:
>>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme
>
>
>