-- argmax xs: index of the maximum element (first occurrence wins on ties).
-- argmin xs: index of the minimum element (first occurrence wins on ties).
-- argsort xs: sorted-index permutation ascending (stable; empty list returns []).
-- Replaces the verbose `srt fn (enumerate xs)` + extract-first pattern.
peak xs:L n>n;argmax xs
valley xs:L n>n;argmin xs
order xs:L n>L n;argsort xs
-- Tie-breaking: first occurrence wins (numpy convention).
first-max>n;argmax [2,2,2]
first-min>n;argmin [5,5,5]
-- argsort on already-sorted input is the identity permutation.
identity>L n;argsort [1,2,3,4,5]
-- argsort on empty list returns empty list.
empty-sort>L n;argsort []
-- run: peak [3,1,4,1,5,9,2,6]
-- out: 5
-- run: valley [3,1,4,1,5,9,2,6]
-- out: 1
-- run: order [3,1,4,1,5,9,2,6]
-- out: [1, 3, 6, 0, 2, 4, 7, 5]
-- run: first-max
-- out: 0
-- run: first-min
-- out: 0
-- run: identity
-- out: [0, 1, 2, 3, 4]
-- run: empty-sort
-- out: []