Hi all! It seems to me that positive? is handled somehow specially by occurrence typing, and that this is not documented but should be.
It appears to have a filter in practice, even the Typed Racket guide [1] claims so in passing, but this filter is not visible in its type annotation, compared e.g. to string?: > string? - : (-> Any Boolean : String) ; <--- Note the filter annotation `: String` #<procedure:string?> > positive? - : (-> Real Boolean) ; <--- No filter annotation! #<procedure:positive?> Therefore, I'm a bit confused by Sec. 5.3. I'm guessing that `positive?` has a more complicated filter (it refines Real to Positive-Real, and Integer to Positive-Integer), and that Sec. 5.2 is in fact oversimplified, but I failed to find mention of filter or `positive?` in the Typed Racket reference [2]. [1] http://docs.racket-lang.org/ts-guide/occurrence-typing.html [2] http://docs.racket-lang.org/search/index.html?q=T:ts-reference%20filter Also queried without results: T:ts-guide positive? T:ts-reference positive? Instead, searching `T:ts-guide filter` leads me to the incomplete discussion above. Cheers, Paolo -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
