Single-helper tail-recursive loop threading an accumulator:
let factorial n =
let rec go n acc =
if n <= 1 then acc
else go (n - 1) (n * acc)
in
go n 1
factorial 12 = 479_001_600
Companion to factorial.ml (10! = 3628800 via doubly-recursive
style); same answer-shape, different evaluator stress: this version
has constant stack depth.
130 baseline programs total — milestone.
giles
63901931c4