On Sun, Apr 29, 2012 at 12:43 PM, Matthias Felleisen <[email protected]> wrote: > > What you're really saying is that sequence-map uses the wrong kind of type. > Specifically, it should be polymorphic in the sequence constructor instead of > mapping everything to the top of the class hierarchy (sequence). > > Interesting point is that you described/found this problem in a type-free > world. > > Question is how we should deal with this in Typed Racket, given our lack of > bounded polymorphism
The Scala collections classes go to a *lot* of work to make this all work nicely in a typed setting. But it's way more than just bounded polymorphism that they use. > > -- Matthias > > > > > On Apr 29, 2012, at 8:12 AM, Jens Axel Søgaard wrote: > >> Given a sequence is there way to get the "constructor" of the sequence? >> >> (sequence-constructor (list 1 2 3)) = list >> (sequence-constructor (vector 1 2 3)) = vector >> etc >> >> I'd like to use it for a declare-mappable macro that extends functions >> of one argument >> to map over sequences. As in (sin (list 1 2 3)) = (list (sin 1) (sin >> 2) (sin 3)). >> >> The sequence-map function is close, but it produces sequences. >> Now I could of course hard code the usual suspects, but it seems >> somewhat inelegant. >> >> -- >> Jens Axel Søgaard >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users -- sam th [email protected] ____________________ Racket Users list: http://lists.racket-lang.org/users
