Hello everyone, I couldn't find anything already created to this
effect so I sat down and did this, I even wrote a little about it
here:
http://www.prodevtips.com/2008/12/25/factorials-permutations-and-recursion-in-pico-lisp/
(de fac (Num)
(let Res 1
(for (N 1 (>= Num N) (inc N))
(setq Res (* Res N)))))
(de switch (Lst P1 P2)
(let (V1 (get Lst P1) V2 (get Lst P2))
(place P1 (place P2 Lst V1) V2)))
(de permutate (Lst)
(let (Result (list) Count 1 Start 1)
(recur (Lst Start Result Count)
(when (>= (fac (length Lst)) Count)
(push Result Lst)
(when (= Start (length Lst)) (setq Start 1))
(recurse
(switch Lst Start (inc Start))
(inc Start)
Result
(inc Count)))
(car Result))))
(permutate '(1 2 3))
I'm sure this could be done more efficiently and with less code,
anyone has any suggestions?
Anyway when this stuff - and I'm sure there is more like it - has been
sanitized/optimized maybe it could constitute some kind of extended
library, lib2.l maybe?
Cheers and happy new year!
/Henrik
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