[feature request] compare about owl HOT 2 CLOSED

let pomap_compare m1 m2 =
  let f acc e1 e2 =
    match acc with
    | Equal -> if e1 < e2 then Lower else 
               if e1 > e2 then Greater else Equal
    | Lower ->   if e1 <= e2 then Lower else Unknown
    | Greater -> if e1 >= e2 then Greater else Unknown
    | Unknown -> Unknown (* should never happen given short circuit *)
  in Utils.short_circuit_fold2 Unknown f Equal m1 m2

let compare m1 m2 =
  let f acc e1 e2 =
    match acc with
         |  0 -> if e1 < e2 then -1 else
                 if e1 > e2 then 1 else 0
         | -1 -> if e1 <= e2 then -1 else failwith "incomparable"
         |  1 -> if e1 >= e2 then  1 else failwith "incomparable"
         |  _ -> failwith "bug: acc is not -1, 0, or 1" (* avoid match warning *)
  in Utils.fold2 f 0 m1 m2