On Sun, Feb 15, 2009 at 1:44 PM, Chouser <chou...@gmail.com> wrote:
> (defn my-interpose [x coll]
> (loop [v [x] coll coll]
> (if (seq coll) ; Don't assume coll is a seq-or-nil
> (recur (-> v (conj (first coll)) (conj x)) (rest coll))
> v)))
You know, there is an empty? predicate. Why not write it as:
(defn my-interpose [x coll]
(loop [v [x] coll coll]
(if (empty? coll) v ; Don't assume coll is a seq-or-nil
(recur (-> v (conj (first coll)) (conj x)) (rest coll)))))
I know that your first version is viewed as more idiomatic in Clojure,
but I've never understood why Rich and others prefer that style. It
assumes that converting something to a seq is guaranteed to be a
computationally cheap operation, and I see no reason to assume that
will always be the case. I can certainly imagine seq-able
collections that take some time seq-ify, so converting to a seq to
test for empty, and then just throwing it away causing it to be
recomputed in rest doesn't seem as future-proof as just using empty?.
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