Perfect numbers: Difference between revisions

=={{header|OCaml}}==

<lang ocaml>let perf n =

let sum = ref 0 in

for i = 1 to n-1 do

if n mod i = 0 then

sum := !sum + i

done;

!sum = n</lang>

Functional style:

<lang ocaml>(* range operator *)

let rec (--) a b =

if a > b then

[]

else

a :: (a+1) -- b

let perf n = n = List.fold_left (+) 0 (List.filter (fun i -> n mod i = 0) (1 -- (n-1)))</lang>