On Jun 14, 2:53 pm, James Reeves <weavejes...@googlemail.com> wrote:
> On Jun 14, 6:32 pm, Wrexsoul <d2387...@bsnow.net> wrote:
>
> > I wrote super-lazy-seq because repeatedly can't generate a finite
> > sequence. It just spat out
>
> > (File1 File2 File3 File4 nil nil nil nil nil nil nil ...
>
> Well, you could wrap it in take-while:
>
> (defn custom-lazy-seq [stream]
> (take-while (complement nil?)
> (repeatedly #(next-item-in-seq stream))))
Eh. That didn't occur to me. It could be combined with the meta-nil
trick, too:
(defn custom-lazy-seq [genfn]
(map #(first %)
(take-while (complement nil?)
(repeatedly genfn))))
where the genfn returns nil for no-next-item and [item] otherwise.
Of course, super-lazy-seq:
a) does the wrapping AND unwrapping for you
b) manages the rebinding each iteration for you,
transparently and
c) works just as well.
The loop/recur style of super-lazy0-seq use seems "closer to
functional purity" than does an explicitly stateful genfn.
One thing is becoming clear: in clojure, there's generally more than
one way to do it. Whatever "it" is.
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