use Fun.protect in bracket

bracket.ml

@@ -1,7 +1,5 @@
 let bracket ~make:(lazy x) ~act ~free =
-  match act x with
-  | result      -> free x; result
-  | exception e -> free x; raise e
+  Fun.protect (fun () -> act x) ~finally:(fun () -> free x)
 
 let infile ~act name =
   bracket ~make:(lazy (open_in name)) ~act ~free:close_in_noerr

day3.ml

@@ -1,38 +1,26 @@
-type space = Tree | Free
-type map = space array array
+type map = string array
 
-let (.%()) arr i = arr.(i mod Array.length arr)
+let (.%[]) str i = str.[i mod String.length str]
+let (+=) r x = r := !r + x
 
 let iter_map ?(step_x=1) ?(step_y=1) f arr =
-  let i = ref 0 in
-  let j = ref 0 in
+  let i = ref 0 in let j = ref 0 in
   while !i < Array.length arr do
-    f arr.(!i).%(!j);
-    i := !i + step_x;
-    j := !j + step_y
+    f arr.(!i).%[!j];
+    i += step_x; j += step_y
   done
 
 
-exception Unknown_char of char
-
-let make_line str =
-  Array.init (String.length str)
-    (fun i -> match str.[i] with
-      | '#' -> Tree
-      | '.' -> Free
-      | c   -> raise (Unknown_char c))
-
-let read_file = Bracket.infile_lines ~line:make_line ~of_seq:Array.of_seq
+let read_file = Bracket.infile_lines ~line:Fun.id ~of_seq:Array.of_seq
 
 
 let count_trees ?step_x ?step_y map =
   let count = ref 0 in
-  iter_map ?step_x ?step_y (function Tree -> incr count | _ -> ()) map;
+  iter_map ?step_x ?step_y (fun c -> if c = '#' then incr count) map;
   !count
 
 let main1 input =
-  Format.printf "%d trees\n"
-    (count_trees ~step_y:3 (read_file input))
+  Format.printf "%d\n" (count_trees ~step_y:3 (read_file input))
 
 let main2 input =
   let map = read_file input in
@@ -47,7 +35,7 @@ let main = Misc.main 3 [|main1; main2|]
 
 let%expect_test _ =
   main1 "../../data/day3";
-  [%expect{| 244 trees |}]
+  [%expect{| 244 |}]
 
 let%expect_test _ =
   main2 "../../data/day3";