If you don't plan to use the &rest arguments, and in fact don't care
about them at all, why are you binding them to something?
More importantly, it would make the following idiom a lot more clumsy:
(defn sum [list]
(let [[x & xs] list]
(+ x (if xs
(sum xs)
0))))
Using rest would cause the xs part to always be true, because to
determine whether the sequence is empty you would have to call seq on
it.
On Mar 23, 6:23 pm, Takahiro Hozumi <fat...@googlemail.com> wrote:
> Hi,
> I think destructure should not produce nthnext, because it realize an
> element of sequence more than needed.
>
> For example:
> (defn inc-seq [i]
> (iterate #(let [x (inc %)] (println "realize:" x) x) i))
> ;=> #'user/inc-seq
>
> (take 1 (inc-seq 0))
> ;=> (0)
>
> (take 1 (let [[x & xs] (inc-seq 0)] (cons x xs)))
> ; realize: 1
> ;=> (0)
>
> (macroexpand '(let [[x & xs] (inc-seq 0)] (cons x xs)))
> ;=> (let* [vec__2630 (inc-seq 0)
> x (clojure.core/nth vec__2630 0 nil)
> xs (clojure.core/nthnext vec__2630 1)]
> (cons x xs))
>
> Although nthrest isn't in clojure, why not to use nthrest instead of
> nthnext in destructure?
> What do you think?
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