Hi,
`contains?` only works with associative data-structures like maps &
vectors. If you want to find out if a sequence contains a specific
object then you need to use `some` paired with a set as a predicate.
For example:
(some #{3} '(1 2 3 4))
Hope this helps.
~BG
On Wed, Aug 7, 2013 at 4:54 PM, Goldritter
<[email protected]> wrote:
> In an program I used the result of keys as an argument for a function which
> verifies whether an object is in a passed collection or not.
> The result I got was following Exception:
> IllegalArgumentException contains? not supported on type:
> clojure.lang.APersistentMap$KeySeq clojure.lang.RT.contains (RT.java:724)
>
> What are the reasons behind this Exception?
>
> In the documentation of contains? it is written, that
> "Returns true if key is present in the given collection, otherwise returns
> false."
> The examples on this page
> (http://clojuredocs.org/clojure_core/clojure.core/contains_q) and the
> parameter description indicates, that contains? accept any collection as
> argument.
>
> The result of keys is also a collection
> => (coll? (keys {:a "f" :b 23}))
> true
>
> So is this a bug or is there a reason behind the fact, that contains? does
> not accept any collection?
> Or is the documentation wrong and it should nor be a collection as argument
> but a set or a vector?
>
> Because I get the same Exception for a list, but not for a vector.
> The same for lists, which returns also true for coll?.
> => (coll? '(1 2 3 4))
> true
>
> => (contains? '(1 2 3 4) 3)
> IllegalArgumentException contains? not supported on type:
> clojure.lang.PersistentList clojure.lang.RT.contains (RT.java:724)
>
> => (contains? [1 2 3 4] 3)
> true
>
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--
Baishampayan Ghose
b.ghose at gmail.com
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