Hi, Am 22.07.2009 um 19:35 schrieb Richard Newman:
Note that predicates don't necessarily have to return literal true or
false: in my opinion at least, it's perfectly reasonable to write
(def my-predicate? #{:foo :bar})
-- it'll behave correctly in if and when, but the return value will
actually be a keyword or nil, not true or false.
Be careful with this. Only do this if you know in advance, that neither false nor nil are in your set. To be safe use contains?, which makes the whole thing again a predicate. (defn my-predicate? [elem] (contains? set-I-have-not-full-control-over elem)) Sincerely Meikel
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