On Feb 19, 6:23 am, Chouser <chou...@gmail.com> wrote:
> In Clojure, if you could use conj on a vector but instead use
> concat on a list, you'll end up with code that is both
> non-idiomatic and runs slower than necessary.
I found the exercise of doing the equivalent with Clojure vectors
pretty challenging. Given the following use case for CL append:
CL-USER> (append '(a) '() '(b (c)) '(d))
(A B (C) D)
The best I could do with Clojure vectors is this:
(defn join-vecs [v1 v2]
(let [v2len (count v2)]
(cond
(zero? v2len) v1
(= v2len 1) (conj v1 (first v2))
true (recur (conj v1 (first v2)) (rest v2)))))
(defn append [& vecs] (reduce join-vecs [] vecs))
user> (append '[a] '[] '[b [c]] '[d])
[a b [c] d]
Is there a better / more idiomatic / more efficient way?
Thanks,
Mike
P.S. I recently got the MEAP of "The Joy of Clojure" and, aside from
a few rough edges in the copy editing, think the content is
excellent! Looking forward to learning more.
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