That’s helpful, but I’m fine with defining my version of name/kw myself (and I have more control over it anyway).
What I’m really trying to do is define a type for typed/racket. Sorry I wasn’t very clear about that. On Jun 7, 2014, at 4:57 AM, Manfred Lotz <manfred.l...@arcor.de> wrote: > Hi Alexander, > I asked this question some time ago: > http://article.gmane.org/gmane.comp.lang.racket.user/3420/match=structure+question > > I got a very good answer from Matthias Felleisen who showed how this > could be achieved: > http://article.gmane.org/gmane.comp.lang.racket.user/3437/match=structure+question > > Hope this helps in some way. > > -- > Manfred > > > > On Fri, 6 Jun 2014 16:59:41 -0400 > "Alexander D. Knauth" > <alexan...@knauth.org> wrote: > >> Is there a way to define a type constructor that accepts keyword >> arguments? >> >> I know that things like the Class type constructor do this already, >> so is there a way to define something like this myself? >> >> The reason is I have a struct that represents a dimension (as in >> dimensional analysis and units) and I want a type constructor that >> lets me make types for specific instances of it without having to >> remember what order the fields go in: >> >> (struct: (Length-Expt Mass-Expt Time-Expt Charge-Expt Temp-Expt) >> dimension >> ([length-expt : Length-Expt] >> [mass-expt : Mass-Expt] >> [time-expt : Time-Expt] >> [charge-expt : Charge-Expt] >> [temperature-expt : Temp-Expt]) >> ) >> >> (define (dimension--kws #:length^ [length-expt 0] >> #:mass^ [mass-expt 0] >> #:time^ [time-expt 0] >> #:charge^ [charge-expt 0] >> #:temperature^ [temp-expt 0]) >> (dimension length-expt mass-expt time-expt charge-expt temp-expt)) >> >> ;; I want to be able to do something that would do the same thing as >> this: (it doesn't have to be this easy) (define-type (Dimmension--kws >> #:length^ Length-Expt #:mass^ Mass-Expt >> #:time^ Time-Expt >> #:charge^ Charge-Expt >> #:temperature^ Temp-Expt) >> (dimension Length-Expt Mass-Expt Time-Expt Charge-Expt Temp-Expt)) >> >> >> > > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
