Quick clojure question, I think this is mostly syntax related. How do I dispatch a multimethod based on specific type signatures of the arguments, for example:
(defn foo
([String a String b] (println a b))
([Long a Long b] (println (+ a b))
([String a Long b] (println a (str b))))
I want to extend this to arbitrary stuff, eg two strings followed by a map, to maps followed by a double, two doubles followed by an IFn etc...
(defn class2 [x y]
[(class x) (class y)])
(defmulti foo class2)
(defmethod foo [String String] [a b]
(println a b))
(defmethod foo [Long Long] [a b]
(println (+ a b)))
From the REPL:
user=> (foo "bar" "baz")
bar baz
nil
user=> (foo 1 2)
3
nil
You could also consider using type instead of class; type returns :type metadata, delegating to class if there is none.
Also, class2 does not have to be defined at top level; passing (fn [x y] ...) as the dispatch function to defmulti is fine too.