[racket] Strange contracts in the tutorial

Ok, now I get what it means.

Still, it feels confusing in the way that it's written.

[]'s

Rodolfo Carvalho


On Mon, Jun 13, 2011 at 20:55, Matthias Felleisen <matthias at ccs.neu.edu>wrote:

>
> The author tried to say it doesn't return.
>
> In a Racket-like context, the author could have specified
>
>  ;; render-blog-page : request -> ∅
>
> Since there are no elements in the emptyset, this specification says the
> same thing mathematically, using Racket's `types as sets' standard form of
> loose reasoning. I doubt it would have been more easily understood.
>
> An MLer could have said α again because it is impossible to return
> something of this type if the function's domain isn't specified as such.
> Would this help?
>
> -- Matthias
>
>
>
>
> On Jun 13, 2011, at 5:13 PM, Rodolfo Carvalho wrote:
>
> Hi,
>
> I'm reading the User Guide: Continue<http://docs.racket-lang.org/continue/> and
> I'm puzzled with some contracts that reads:
>
>  ; render-blog-page: request -> doesn't ; Produces an doesn't page of the
>> content of the ; BLOG.
>
>
>
> Is it correct? What does it mean that it "produces an doesn't"?
>
> []'s
>
> Rodolfo Carvalho
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