On 08.03.2009, at 00:14, mikel wrote: > You can do a lot of that in Clojure, too, but, unless I'm mistaken, > there are some arbitrary limits as things stand right now. I don't > know of a way in Clojure to define an interface; as far as I know, if
Multimethods can be used very well to define interfaces. > you decide you need a new interface, you have to step outside Clojure > to define it. And you can have any kind of structure you want, as long > as it's a map, set, or sequence. Or anything definable in terms of these. Look at clojure.contrib.types, for examples, to see how these elements can be used to implement algebraic data types. > arbitrary data layouts. That's half the picture. What about the other > half? How would one go about defining a new interface using only > Clojure code? There are some examples of multimethods-as-interfaces in clojure.contrib: 1) clojure.contrib.seq-utils/seq-on You can implement this multimethod for whatever type to have it converted to a seq. 2) clojure.contrib.types.examples/fmap A Haskell-like functor interface (if people really want to use this, I'd happily move it somewhere else than an example script). 3) clojure.contrib.stream-utils/stream-next A data stream interface. I am actively working on this one, my current version is already much nicer than the one currently in SVN, so wait a few days before looking at this :-) The big difference compared to Haskell's classes is that everything is based on dynamic typing, so the compiler cannot verify or enforce the correct use of interfaces. That's part of Clojure's (and Lisp's) design, the tradeoffs between static and dynamic typing being well known by now. Konrad. --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
