flatten array of array in grid implementation

makes the new find function much simpler to implement

.ocamlinit

@@ -1 +1,2 @@
 #install_printer Aoc.Vec2.pp;;
+#install_printer Aoc.Vec2.pp_grid;;

src/vec2.ml

@@ -1,7 +1,13 @@
 open Containers
 
 type t = int * int [@@deriving show]
-type 'a grid = 'a array array
+
+type 'a grid =
+  { width : int
+  ; height : int
+  ; items : 'a array
+  }
+[@@deriving show]
 
 let up = 0, 1
 let down = 0, -1
@@ -14,24 +20,40 @@ let ( + ) a b = Pair.map_same2 ( + ) a b
 let ( - ) a b = Pair.map_same2 ( - ) a b
 let ( = ) a b = Pair.equal ( = ) ( = ) a b
 
-let at grid point =
-  let x, y = to_tuple point in
+let at (grid : 'a grid) (point : t) =
+  let x, y = point in
+  if x >= 0 && x < grid.width && y >= 0 && y < grid.height
+  then Array.get_safe grid.items @@ Int.((grid.width * y) + x)
+  else None
+;;
+
+let find (grid : 'a grid) pred =
   let open Option.Infix in
-  let* row = Array.get_safe grid y in
-  Array.get_safe row x
+  let* idx, _ = Array.find_idx pred grid.items in
+  let y = idx / grid.width in
+  let x = idx mod grid.width in
+  Some (x, y)
 ;;
 
-let parse_grid parse_char lines =
-  lines
-  |> Array.of_list
-  |> Array.map Fun.(String.to_seq %> Seq.map parse_char %> Seq.to_array)
+let parse_grid parse_char lines : 'a grid =
+  match lines with
+  | first_line :: _ ->
+    let width = String.length first_line in
+    let height = List.length lines in
+    let yeet =
+      lines
+      |> List.map String.to_list
+      |> List.flatten
+      |> List.map parse_char
+      |> Array.of_list
+    in
+    { width; height; items = yeet }
+  | _ -> failwith "somethin fucd up"
 ;;
 
-let iter_grid grid callback =
-  let grid_h = Array.length grid in
-  let grid_w = Array.length grid.(0) in
-  for y = 0 to Int.(grid_h - 1) do
-    for x = 0 to Int.(grid_w - 1) do
+let iter_grid (grid : 'a grid) callback =
+  for y = 0 to Int.(grid.height - 1) do
+    for x = 0 to Int.(grid.width - 1) do
       callback (x, y)
     done
   done

src/vec2.mli

@@ -1,5 +1,5 @@
 type t [@@deriving show]
-type 'a grid
+type 'a grid [@@deriving show]
 
 val up : t
 val down : t
@@ -13,4 +13,5 @@ val ( - ) : t -> t -> t
 val ( = ) : t -> t -> bool
 val at : 'a grid -> t -> 'a option
 val parse_grid : (char -> 'a) -> string list -> 'a grid
+val find : 'a grid -> ('a -> bool) -> t option
 val iter_grid : 'a grid -> (t -> unit) -> unit