Formatter causes precedence errors

[mariari]

I wrote the following function, it loads OK

monotonically-increasing? {A} {{Ord A}} : List A -> Bool
  | [] := true
  | (x :: xs) :=
    for (acc, res := x, true) (x in xs) {
         (x, (acc < x && res))
      }
      |> snd;

However if I were to format this file it becomes:

monotonically-increasing? {A} {{Ord A}} : List A -> Bool
  | [] := true
  | (x :: xs) :=
    for (acc, res := x, true) (x in xs) {
         x, acc < x && res
      }
      |> snd;

Which causes the following error

Operators , and < have incomparable precedences
ExitFailure 1