On Jun 16, 2014, at 2:53 PM, Sam Tobin-Hochstadt <sa...@cs.indiana.edu> wrote:
> This is exactly what predicates are for, in general. However, you > can't have predicates that check things about functions -- there's no > information there at runtime to look at. I was kind of wondering if there was anything that could make the type checker put something there for runtime to look at. > Typed Racket functions are > just plain Racket functions. We could add some extra metadata to every > value that held its type, It wouldn’t have to be every value, it could just put that information in for :has-type expressions, right? Would that still require fundamental changes to Racket? > and then implement this operation, but that > would require fundamental changes to Racket. > > Even if we wanted to do that, what if `f` came in from untyped Racket? If f comes from untyped Racket, then the type checker says to use require/typed to import it. > > Sam > > On Mon, Jun 16, 2014 at 2:49 PM, Alexander D. Knauth > <alexan...@knauth.org> wrote: >> Would there be a way to test the type for making decisions at run-time (not >> just with predicates)? >> >> For example: >> (cond [(:has-type? f (Number -> Any)) >> (f 1)] >> [(:has-type? f (String -> Any)) >> (f "1")]) >> >> On Jun 16, 2014, at 6:54 AM, Matthias Felleisen <matth...@ccs.neu.edu> >> wrote: >> >> >> That's what I thought you wanted it for so my answer stands -- Matthias >> >> >> >> On Jun 15, 2014, at 12:55 AM, Spencer Florence wrote: >> >> This is about making decisions at compile time. Specifically I have a >> sequence of expressions I want to partition into expressions of some type T >> and expressions of other types. >> >> >> On Sat, Jun 14, 2014 at 7:34 PM, Robby Findler <ro...@eecs.northwestern.edu> >> wrote: >>> >>> Would it be enough to expand into an 'ann' expression? Or do you need >>> to make decisions at compile time based on whether or not the types >>> worked? >>> >>> Robby >>> >>> On Sat, Jun 14, 2014 at 2:04 PM, Matthias Felleisen >>> <matth...@ccs.neu.edu> wrote: >>>> >>>> No, TR expands first, then checks. -- Matthias >>>> >>>> >>>> >>>> >>>> On Jun 14, 2014, at 2:59 PM, Spencer Florence wrote: >>>> >>>>> Hey All, >>>>> >>>>> I'm trying to take advantage of typed/racket in a few macros. Is there >>>>> any way to check the type of an expression from its syntax object? >>>>> something >>>>> like: >>>>> >>>>> (:has-type? (-> Void) #'expression) >>>>> >>>>> >>>>> --Spencer >>>>> ____________________ >>>>> Racket Users list: >>>>> http://lists.racket-lang.org/users >>>> >>>> >>>> ____________________ >>>> Racket Users list: >>>> http://lists.racket-lang.org/users >> >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users >> >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users >> ____________________ Racket Users list: http://lists.racket-lang.org/users
