Hi,
Am 07.02.2011 um 18:20 schrieb Justin Kramer:
> Checking out clojure.core/destructure and clojure.core/let might be
> helpful.
>
> Here's a macro I hacked together. It doesn't work with :keys, :as,
> or :or. I take no responsibility if you use it for anything real. But
> maybe it will provide you with some ideas.
>
> (defmacro destructure->map
> [bvec val]
> `(let [~bvec ~val]
> (-> {}
> ~@(for [s (remove #(= '& %) (flatten bvec))]
> `(assoc (-> (quote ~s) name keyword) ~s)))))
>
> Example:
>
> (let [v [1 2 [3 4 5 6 7 8]]]
> (destructure->map [a b [c d & e]] v))
> => {:e (5 6 7 8), :d 4, :c 3, :b 2, :a 1}
Straight-forward, ugly loop solution:
(defn destruct
[pattern coll]
(loop [ps (seq pattern)
s (seq coll)
ls {}]
(let [local (first ps)]
(cond
; patterns exhausted? done
(nil? ps)
ls
; "local" is a seq? => descent
(seq? local)
(recur (next ps) (next s) (merge ls (destruct local (first s))))
; "local" is something & like? => bind the rest and done.
(= "&" (name local))
(assoc ls (second ps) s)
; default => bind the local in the map.
:else
(recur (next ps) (next s) (assoc ls local (first s)))))))
user=> (destruct '(a b (c d & e)) [1 2 [3 4 5 6 7 8]])
{c 3, d 4, e (5 6 7 8), b 2, a 1}
Sincerely
Meikel
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