Definitely something that should not written as a macro :)
David
On Thu, Jun 14, 2012 at 1:14 PM, Jim - FooBar(); <jimpil1...@gmail.com>wrote:
> 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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