Simplify code with Option.{map,bind}

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>

src/context.ml

@@ -178,13 +178,12 @@ let create ~(kind : Kind.t) ~path ~env ~env_nodes ~name ~merlin ~targets
     >>= fun findlib_config ->
 
     let get_tool_using_findlib_config prog =
-      Option.bind findlib_config ~f:(fun conf ->
-        match Findlib.Config.get conf prog with
-        | None -> None
-        | Some s ->
-          match Filename.analyze_program_name s with
-          | In_path | Relative_to_current_dir -> which s
-          | Absolute -> Some (Path.of_filename_relative_to_initial_cwd s))
+      let open Option.O in
+      findlib_config >>= fun conf ->
+      Findlib.Config.get conf prog >>= fun s ->
+      match Filename.analyze_program_name s with
+      | In_path | Relative_to_current_dir -> which s
+      | Absolute -> Some (Path.of_filename_relative_to_initial_cwd s)
     in
 
     let ocamlc =

src/dune_file.ml

@@ -1144,9 +1144,8 @@ module Executables = struct
       let is_ok (_, candidate) =
         compare candidate link_mode = Eq
       in
-      match List.find ~f:is_ok simple_representations with
-      | Some (s, _) -> Some (Dsexp.unsafe_atom_of_string s)
-      | None -> None
+      List.find ~f:is_ok simple_representations
+      |> Option.map ~f:(fun (s, _) -> Dsexp.unsafe_atom_of_string s)
 
     let dgen link_mode =
       match simple_dgen link_mode with
@@ -1287,13 +1286,12 @@ module Executables = struct
           in
           List.map2 names public_names
             ~f:(fun (_, name) (_, pub) ->
-              match pub with
-              | None -> None
-              | Some pub -> Some ({ Install_conf.
-                                    src = name ^ ext
-                                  ; dst = Some pub
-                                  }))
-          |> List.filter_map ~f:(fun x -> x)
+              Option.map pub ~f:(fun pub ->
+                { Install_conf.
+                  src = name ^ ext
+                ; dst = Some pub
+                }))
+          |> List.filter_opt
       in
       match to_install with
       | [] -> begin

src/findlib.ml

@@ -304,9 +304,9 @@ let find_and_acknowledge_meta t ~fq_name =
         else
           loop dirs
     | [] ->
-      match String.Map.find t.builtins root_name with
-      | Some meta -> Some (t.stdlib_dir, Path.of_string "<internal>", meta)
-      | None -> None
+      String.Map.find t.builtins root_name
+      |> Option.map ~f:(fun meta ->
+        (t.stdlib_dir, Path.of_string "<internal>", meta))
   in
   match loop t.path with
   | None ->

src/installed_dune_file.ml

@@ -4,13 +4,13 @@ let parse_sub_systems ~parsing_context sexps =
   List.filter_map sexps ~f:(fun sexp ->
     let name, ver, data =
       Dsexp.Of_sexp.(parse (triple string (located Syntax.Version.dparse) raw)
-                      parsing_context) sexp
+                       parsing_context) sexp
     in
     (* We ignore sub-systems that are not internally known. These
        correspond to plugins that are not in use in the current
        workspace. *)
-    Option.bind (Sub_system_name.get name) ~f:(fun name ->
-      Some (name, (Dsexp.Ast.loc sexp, ver, data)))
+    Option.map (Sub_system_name.get name) ~f:(fun name ->
+      (name, (Dsexp.Ast.loc sexp, ver, data))))
   |> Sub_system_name.Map.of_list
   |> (function
     | Ok x -> x

src/ocaml-config/ocaml_config.ml

@@ -261,13 +261,11 @@ module Vars = struct
           fail "Value of %S is neither 'true' neither 'false': %s." var s
 
     let get_int_opt t var =
-      match get_opt t var with
-      | None -> None
-      | Some s ->
+      Option.bind (get_opt t var) ~f:(fun s ->
         match int_of_string s with
         | x -> Some x
         | exception _ ->
-          fail "Value of %S is not an integer: %s." var s
+          fail "Value of %S is not an integer: %s." var s)
 
     let get_words t var =
       match get_opt t var with

src/scope.ml

@@ -77,19 +77,17 @@ module DB = struct
     let public_libs =
       let public_libs =
         List.filter_map internal_libs ~f:(fun (_dir, lib) ->
-          match lib.public with
-          | None -> None
-          | Some p -> Some (Dune_file.Public_lib.name p, lib.project))
+          Option.map lib.public ~f:(fun p ->
+            (Dune_file.Public_lib.name p, lib.project)))
         |> String.Map.of_list
         |> function
         | Ok x -> x
         | Error (name, _, _) ->
           match
             List.filter_map internal_libs ~f:(fun (_dir, lib) ->
-              match lib.public with
-              | None   -> None
-              | Some p -> Option.some_if (name = Dune_file.Public_lib.name p)
-                            lib.buildable.loc)
+              Option.bind lib.public ~f:(fun p ->
+                Option.some_if (name = Dune_file.Public_lib.name p)
+                  lib.buildable.loc))
           with
           | [] | [_] -> assert false
           | loc1 :: loc2 :: _ ->

src/stdune/list.ml

@@ -14,6 +14,14 @@ let rec filter_map l ~f =
     | None -> filter_map l ~f
     | Some x -> x :: filter_map l ~f
 
+let rec filter_opt l =
+  match l with
+  | [] -> []
+  | x :: l ->
+    match x with
+    | None -> filter_opt l
+    | Some x -> x :: filter_opt l
+
 let filteri l ~f =
   let rec filteri l i =
     match l with

src/stdune/list.mli

@@ -6,6 +6,8 @@ val is_empty : _ t -> bool
 
 val filter_map : 'a t -> f:('a -> 'b option) -> 'b t
 
+val filter_opt : 'a option t -> 'a t
+
 val filteri : 'a t -> f:(int -> 'a -> bool) -> 'a t
 
 val concat_map : 'a t -> f:('a -> 'b t) -> 'b t