CCFormat(feat): add option and result, change opt

Add CCFormat.option and CCFormat.result as aliases to
Format.pp_print_option and Format.pp_print_result. Make CCFormat.opt an
alias of CCFormat.option, as such this add an optional argument to print
the case "None" but change the default behaviour. Previously, it as
printing "some _" or "none" now it print something only in the case of
"Some x" and just "x".

src/core/CCFormat.ml

@@ -31,6 +31,9 @@ let break fmt (m, n) = Format.pp_print_break fmt m n
 let newline = Format.pp_force_newline
 let substring out (s, i, len) : unit = string out (String.sub s i len)
 let text = Format.pp_print_text
+let option = Format.pp_print_option
+let opt = option
+let result = Format.pp_print_result
 
 let string_lines out (s : string) : unit =
   fprintf out "@[<v>";
@@ -88,11 +91,6 @@ let iter ?(sep = return ",@ ") pp fmt seq =
         sep fmt ();
       pp fmt x)
 
-let opt pp fmt x =
-  match x with
-  | None -> Format.pp_print_string fmt "none"
-  | Some x -> Format.fprintf fmt "some %a" pp x
-
 let pair ?(sep = return ",@ ") ppa ppb fmt (a, b) =
   Format.fprintf fmt "%a%a%a" ppa a sep () ppb b
 

src/core/CCFormat.mli

@@ -99,10 +99,16 @@ val arrayi : ?sep:unit printer -> (int * 'a) printer -> 'a array printer
 val seq : ?sep:unit printer -> 'a printer -> 'a Seq.t printer
 val iter : ?sep:unit printer -> 'a printer -> 'a iter printer
 
-val opt : 'a printer -> 'a option printer
-(** [opt pp] prints options as follows:
-    - [Some x] will become "some foo" if [pp x ---> "foo"].
-    - [None] will become "none". *)
+val option : ?none:unit printer -> 'a printer -> 'a option printer
+(** [opt ?none pp] prints options as follows:
+        - [Some x] will become [pp x]
+        - [None] will become [none ()]
+    @since NEXT_RELEASE *)
+
+val opt : ?none:unit printer -> 'a printer -> 'a option printer
+(** Alias of {!option} *)
+
+val result : ok:'a printer -> error:'e printer -> ('a, 'e) result printer
 
 (** In the tuple printers, the [sep] argument is only available.
     @since 0.17 *)