On Sat, Apr 2, 2011 at 11:38 PM, Stefan Rohlfing
<stefan.rohlf...@gmail.com> wrote:
> I am sure there is a standard functional way of comparing adjacent items in
> a coll and would be glad if someone could point me to it.
(defvar- sentinel (Object.))
(defn take-by [f coll]
(let [fs (map f coll)
ps (map = fs (rest fs))
zs (map #(if %1 %2 sentinel) ps coll)]
(take-while (partial not= sentinel) zs))
user=> (take-by #(mod % 3) [1 4 1 7 34 16 10 2 99 103 42])
(1 4 1 7 34 16)
I leave drop-by as an exercise for the reader, but the punch line here
is (map foo s (rest s)). :)
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