For complex cases, you may like to fall back on multi-methods and abstraction types. I blogged about typed abstractions few days ago here:
http://bitumenframework.blogspot.com/2010/10/typed-abstractions-in-clojure.html Regards, Shantanu On Nov 4, 1:25 pm, "nicolas.o...@gmail.com" <nicolas.o...@gmail.com> wrote: > I see your point. > Somehow, it is annoying to have to manipulate a set of protocols that > always go together. > And it would be nice to have a shorthand. > > I have a very small prototype here: > > git://nicolasoury.repositoryhosting.com/nicolasoury/type-classes.git > > of some code to allow "type-classes" like deductions of protocols (ie > logical programming with protocols). > > It is not really working, tested, maintained or nice currently. > (It was just a quick proof of concept) > > The idea is to write a rule: > > Serializable, Comparable, HalfCool => Cool {implemenation of > functions that are not in the pre-condition} > > Typically if you roll you own Eq protocol with eq, > > Comparable => Eq {:eq (fn [x y] (compare x y)} > > Then, for each protocol accessible on a right handside of a rule, it > extends Object with that protocol. > > This default implementation try to apply all rules, in order to deduce > an implementation. > If it deduces an implementation, it extends the protocol with that > implementation, for the type of the argument. > (That way there is a derivation of implementation only on the first call) > > The implementation is very bad (and not maintained) and I wouldn't > advise using it, but the idea can be useful sometimes. > > Especially, it shows that the access you have to protocols at the > programmatic level, might help to solve the kind of problems you have. > (this kind of deduction are a bit of an overkill for the problem at hand) > > I don't know if there is a similar programmatic access to deftype. I > would like to know of it if there is. > > Best, > > Nicolas. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
