Removing useless function

The function `partition_map` was only used by the case splits dispatcher
of `Relation.ml`. We don't need this function anymore after refactoring
this dispatcher.

src/lib/util/lists.ml

@@ -84,18 +84,3 @@ let rec equal eq l1 l2 =
   | [], [] -> true
   | hd1 :: tl1, hd2 :: tl2 when eq hd1 hd2 -> equal eq tl1 tl2
   | _ -> false
-
-let partition_map ?(keep_ordering=true) f l =
-  let rec part left right = function
-    | [] ->
-      if keep_ordering then List.rev left, List.rev right
-      else left, right
-    | x :: l ->
-      let left, right =
-        match f x with
-        | Ok x   -> x :: left, right
-        | Error x -> left, x :: right
-      in
-      part left right l
-  in
-  part [] [] l

src/lib/util/lists.mli

@@ -64,11 +64,3 @@ val equal : ('a -> 'a -> bool) -> 'a list -> 'a list -> bool
     respectively, we have [eq ai bi].
 
     This is a backport of List.equal from OCaml 4.12.0 *)
-
-val partition_map :
-  ?keep_ordering:bool ->
-  ('a -> ('b, 'c) result) -> 'a list -> 'b list * 'c list
-(** Similar to List.partition, but also applies a map on the elements
-    of the resulting lists on the fly. Ordering of elements will not be
-    kept if [keep_ordering] is unset (Default value is [keep_ordering =
-    true]), in which case, resulting lists are reverted *)