you can always make your own with a little macro but if you just started learning today you may want to stick with some...

I, like you, wanted a version that returns true or false a couple of months ago.. here it is:

(defmacro in?
 "Returns true if colle contains elm, false otherwise."
 [colle elm]
`(if (some #{~elm} ~colle) true false))

Hope that helps...notice this is a macro not a function - the call to in? will expand at compile time into the body of the macro...in other words you've just created some new syntax!

Jim




On 14/06/12 16:31, Jacobo Polavieja wrote:
Hi!

I've just started learning Clojure today. I've started reading "Clojure - Functional Programming for the JVM" (http://java.ociweb.com/mark/clojure/article.html <http://java.ociweb.com/mark/clojure/article.html#Collections>).

Anyway, on the collections part (http://java.ociweb.com/mark/clojure/article.html#Collections) it called my attention that 'some' returns "nil" instead of "false". The examples given (being stooges a vector of Strings) are:

(not-every? #(instance? String %) stooges) ; -> false
(some #(instance? Number %) stooges) ; -> nil

Is there a reason why (some) doesn't return false also? I've read through the doc but as I supposed, there's no explanation about the reasoning behind it.

Thanks!
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