Hi, Am 07.02.2009 um 22:19 schrieb samppi:
(defmacro bar [factor arg] `(foo ~@(replicate factor arg))) ...but then when I use it I get a ClassCastException if I try to do something like (bar (dec 5) something), because then Clojure tries to evaluate (replicate '(dec 5) 'something). So how should I rewrite bar to behave like bar-fn, then?
The point is: you can't! Macros cannot depend on runtime information. And the value function call (dec 5) is runtime information. There is an apply macro in clojure.contrib: http://code.google.com/p/clojure-contrib/source/browse/trunk/src/clojure/contrib/apply_macro.clj The warnings in there are there for a reason. For more information simply search the google group for apply and macro. This should give plenty of other information concerning this issue. Sincerely Meikel
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