Hi,

I think it's by design.

It only works with concrete data structure (list, vector, queue) types that
implement

clojure.lang.IPersistentStack

Las




2013/6/20 Jason Gilman <jason.gil...@gmail.com>

> Also, I really appreciate anyone who takes the time to answer. My company
> is currently evaluating Clojure. I'm trying to determine if this is
> non-idiomatic use of the language or some other issue. Doing something like
> this can cause the bug to occur without directly calling seq on a vector:
>
> (defn bar [my-list n]
>   (if (= n 0)
>       (peek my-list)
>       (bar (rest my-list) (dec n))))
> (bar [1 2 3] 1)
>
> Both rest and peek work on a vector without a problem but the combination
> of the two causes problems.
>
> On Thursday, June 20, 2013 3:54:43 PM UTC-4, Jason Gilman wrote:
>>
>> Why does (peek (seq [1])) result in:
>> ClassCastException clojure.lang.PersistentVector$**ChunkedSeq cannot be
>> cast to clojure.lang.IPersistentStack  clojure.lang.RT.peek (RT.java:634)
>>
>> Peek documentation "For a list or queue, same as first, for a vector,
>> same as, but much more efficient than, last. If the collection is empty,
>> returns nil." implies that there shouldn't be a problem working with
>> vectors.
>>
>> This works without issue:
>> (peek [1])
>>
>> This is on Clojure 1.5.1
>>
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-- 
László Török

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