I made some tests, and if I am not mistaken, if an eos is not
specifically specified, Object is used, is that right?
user=>
(let [iter (stream-iter (range 5))]
(def s (stream (fn [eos]
(let [x (next! iter eos)]
(if (= eos x)
(do (println eos) eos)
x))))))
#'user/s
user=> (seq s)
(0 1 2 3 #<Object java.lang.obj...@25c828>
4)
Vincent
On Jan 21, 7:59 pm, Rich Hickey <richhic...@gmail.com> wrote:
> On Jan 21, 7:40 pm, Vincent Foley <vfo...@gmail.com> wrote:
>
> > I have a question regarding the examples, specifically map* and
> > filter*
>
> > (defn map* [f coll]
> > (let [iter (stream-iter coll)]
> > (stream
> > (fn [eos]
> > (let [x (next! iter eos)]
> > (if (= eos x) x (f x)))))))
>
> > (take 4 (map* inc (filter* even? (range 1000000))))
> > -> (1 3 5 7)
>
> > How is eos passed to the fn inside stream and what is it?
>
> The caller provides eos in calls to the (next! iter eos), which in
> turn passes it to the generator. The caller should choose a value for
> eos that will not be present in the set of items, which can easily be
> created by calling (Object.), as is done by reduce*.
>
> I've enhanced the docs to explain this, and commented the example.
>
> Rich
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