Use same printer for both parts

We want to change Aoc.main to take a single printer parameter to
simplify the run process.

bin/day2417.ml

@@ -129,7 +129,8 @@ let rec execute_until_halted vm =
   | false -> execute_until_halted (execute_insn vm)
 
 (** [string_of_ouput vm] gives the output of [vm]. *)
-let string_of_output vm =
+let part1 vm =
+  let vm = execute_until_halted vm in
   List.rev vm.out |> List.map string_of_int |> String.concat ","
 
 (** [scan_digit acc ip vm] updates the acc for A so that the output of running
@@ -159,8 +160,8 @@ let scan_all vm =
   impl 0 (Array.length vm.code - 1)
 
 (** [string_of_a vm] returns the A register of [vm]. *)
-let string_of_a vm = string_of_int vm.a
+let part2 vm =
+  let vm = scan_all vm in
+  string_of_int vm.a
 
-let _ =
-  Aoc.main vm_of_file
-    [ (string_of_output, execute_until_halted); (string_of_a, scan_all) ]
+let _ = Aoc.main vm_of_file [ (Fun.id, part1); (Fun.id, part2) ]