Folding list of ADT items into pair of options

gistfile1.ml

open Printf

type t = A of string * float | B of int * float

let l = [A ("a1", 0.); B (1, 1.); A ("a2", 1.1); A ("a3",1.2); B (2,1.1)]

let f = fun l ->
	List.fold_left
		(fun (a,b) it ->
			match it,a,b with
			| A (s,t), None, _ -> Some it, b
			| A (s,t), Some (A (s',t')), _  -> if t > t' then Some it, b else a,b
			| B (i,t), _, None -> a, Some it
			| B (i,t), _, Some (B (i', t')) -> if t > t' then a, Some it else a,b
			| _ -> a,b
		) (None, None) l

let a,b = f l

let _ = match a with
	| Some (A (s,t)) -> printf "%s -> %f\n" s t
	| _ -> printf "None\n"

let _ = match b with
	| Some (B (i,t)) -> printf "%d -> %f\n" i t
	| _ -> printf "None\n" ;;