Something like this will give you what you want:
(defn subseqx
[s start end]
(cond
(instance? clojure.lang.IPersistentVector s)
(subvec s start end)
(instance? java.lang.String s)
(subs s start end)
:else
(let [slice (drop start (take end s))]
(cond
(instance? clojure.lang.IPersistentList s)
(apply list slice)
(instance? clojure.lang.PersistentTreeSet s)
(apply sorted-set slice)
(instance? clojure.lang.PersistentTreeMap s)
(apply sorted-map (concat slice))
:else
slice))))
And you can add conditions for other kinds of ordered collections if and
when a need arises. This is neither simple nor pretty, but an advantage
of no-side-effects functional programming is that when you call a pure
function you don't need to worry about how simple or pretty might be its
internal details.
--Larry
On 6/27/12 3:24 PM, Warren Lynn wrote:
Thanks, but this does not keep the concrete type.
On Wednesday, June 27, 2012 3:42:25 PM UTC-4, Ulises wrote:
> I'd forgotten that 'into adds things in the "default" place for
whatever type you're using, hence the reversal on lists. I'm not
sure if there's a simple way to get the same type out again while
preserving order.
How about:
(defn sub-seq [start end coll]
(take (- end start) (drop start coll)))
U
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