Add List.assoc

Signed-off-by: Jeremie Dimino <jdimino@janestreet.com>

src/main.ml

@@ -218,7 +218,7 @@ let bootstrap () =
       Arg.Symbol
         (List.map Config.Display.all ~f:fst,
          fun s ->
-           display := Some (List.assoc s Config.Display.all))
+           display := List.assoc Config.Display.all s)
     in
     let concurrency = ref None in
     let concurrency_arg x =

src/stdune/list.ml

@@ -97,3 +97,8 @@ let rec compare a b ~compare:f : Ordering.t =
     match (f x y : Ordering.t) with
     | Eq -> compare a b ~compare:f
     | ne -> ne
+
+let rec assoc t x =
+  match t with
+  | [] -> None
+  | (k, v) :: t -> if x = k then Some v else assoc t x

src/stdune/list.mli

@@ -36,3 +36,5 @@ val        sort : 'a t -> compare:('a -> 'a -> Ordering.t) -> 'a t
 val stable_sort : 'a t -> compare:('a -> 'a -> Ordering.t) -> 'a t
 
 val compare : 'a t -> 'a t -> compare:('a -> 'a -> Ordering.t) -> Ordering.t
+
+val assoc : ('a * 'b) t -> 'a -> 'b option

src/utils.ml

@@ -60,9 +60,9 @@ let signal_name =
     ]
   in
   fun n ->
-    match List.assoc n table with
-    | exception Not_found -> sprintf "%d\n" n
-    | s -> s
+    match List.assoc table n with
+    | None -> sprintf "%d\n" n
+    | Some s -> s
 
 type target_kind =
   | Regular of string * Path.t

test/blackbox-tests/cram.mll

@@ -24,9 +24,9 @@ and postprocess tbl b = parse
   | eof { Buffer.contents b }
   | ([^ '/'] as c) (ext as e)
       { Buffer.add_char b c;
-        begin match List.assoc e tbl with
-        | res -> Buffer.add_string b res
-        | exception Not_found -> Buffer.add_string b e
+        begin match List.assoc tbl e with
+        | Some res -> Buffer.add_string b res
+        | None     -> Buffer.add_string b e
         end;
         postprocess tbl b lexbuf
       }