[Kernel] Persistent array: slightly simplifies [pretty] function.

Uses the same convention as Pretty_utils.

src/kernel_services/analysis/filter/linear.ml

@@ -38,8 +38,7 @@ module Space (Field : Field.S) = struct
   module Vector = struct
 
     let pretty (type n) fmt (M { data ; _ } : n vector) =
-      let pp_sep fmt () = Format.fprintf fmt "@ " in
-      Parray.pretty ~pp_sep Field.pretty fmt data
+      Parray.pretty ~sep:"@ " Field.pretty fmt data
 
     let init size f =
       let data = Parray.init (Nat.to_int size) (fun _ -> Field.zero) in

src/libraries/utils/parray.ml

@@ -36,10 +36,10 @@ let rec reroot t =
     t' := Diff (i, v', t) ;
     mem
 
-let pretty ?(pp_sep = Format.pp_print_space) pp fmt t =
+let pretty ?(sep = format_of_string " ") pp fmt t =
   let mem = reroot t in
   for i = 0 to Array.length mem - 1 do
-    if i > 0 then pp_sep fmt () ;
+    if i > 0 then Format.fprintf fmt sep ;
     pp fmt mem.(i)
   done
 

src/libraries/utils/parray.mli

@@ -33,6 +33,6 @@ val fold : (int -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
 val map  : ('a -> 'a) -> 'a t -> 'a t
 
 val pretty :
-  ?pp_sep : (Format.formatter -> unit -> unit) ->
+  ?sep : Pretty_utils.sformat ->
   (Format.formatter -> 'a -> unit) ->
   Format.formatter -> 'a t -> unit