contains? is possibly poorly named, contains-key? would probably have
avoided this entire issue. That said, I'd like to see contains? return
false for things where it doesn't make sense, longs, keywords, etc. For a
list, it seems like converting the list to a vectoc (via vec) would be a
reasonable solution, though I'm sure there's some side effect that I
haven't considered. Perf would be impacted, but this doesn't seem like the
kind of thing you'd want to do anyway, so having poor perf wouldn't be the
end of the world. At least it wouldn't exception out.
On Wed, Aug 7, 2013 at 8:14 AM, Jonathan Fischer Friberg <
odysso...@gmail.com> wrote:
> That's only obvious if you already know how it works.
>
> Jonathan
>
>
> On Wed, Aug 7, 2013 at 2:13 PM, Karsten Schmidt <toxmeis...@gmail.com>wrote:
>
>> The fact, that the docs refer to checking if a "key" is present in the
>> collection, should make it obvious which types are supported, no? Only
>> vectors, maps and sets have keys. Lists and seqs do not. Of course it never
>> hurts to be more explicit about it...
>> On 7 Aug 2013 12:49, "Marcus Lindner" <
>> marcus.goldritter.lind...@gmail.com> wrote:
>>
>>> Thanks.
>>>
>>> But the problem is, that this is not mentioned in the documentation of
>>> contains? I found so far :(.
>>> I had such a problem a long time ago and remember now which type of
>>> "collection" can be used with contains?. But after a time I will forget
>>> this again and will refer to the documentation. (And when I get the
>>> Exception I remember again.)
>>>
>>> And I think this question arise also more frequently.
>>>
>>> But then my assumption that the documentation of contains? is misleading
>>> is true. Is it possible to update the documentation for the next version?
>>>
>>>
>>>
>>>
>>>
>>>
>>> 2013/8/7 Baishampayan Ghose <b.gh...@gmail.com>
>>>
>>>> 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
>>>> <marcus.goldritter.lind...@gmail.com> 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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>>>>
>>>>
>>>> --
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>>>> b.ghose at gmail.com
>>>>
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