change Vec2 implementation to a record type

src/vec2.ml

@@ -1,15 +1,19 @@
 open Containers
 
-type t = int * int [@@deriving show]
+type t =
+  { x : int
+  ; y : int
+  }
+[@@deriving show]
 
-let origin = 0, 0
-let up = 0, 1
-let down = 0, -1
-let left = -1, 0
-let right = 1, 0
+let origin = { x = 0; y = 0 }
+let up = { x = 0; y = 1 }
+let down = { x = 0; y = -1 }
+let left = { x = -1; y = 0 }
+let right = { x = 1; y = 0 }
 let directions = [ up; down; left; right ]
-let of_tuple x = x
-let to_tuple x = x
-let ( + ) a b = Pair.map_same2 ( + ) a b
-let ( - ) a b = Pair.map_same2 ( - ) a b
-let ( = ) a b = Pair.equal ( = ) ( = ) a b
+let of_tuple (x, y) = { x; y }
+let to_tuple { x; y } = x, y
+let ( + ) a b = { x = a.x + b.x; y = a.y + b.y }
+let ( - ) a b = { x = a.x - b.x; y = a.y - b.y }
+let ( = ) a b = a.x = b.x && a.y = b.y

src/vec2.mli

@@ -1,4 +1,8 @@
-type t [@@deriving show]
+type t =
+  { x : int
+  ; y : int
+  }
+[@@deriving show]
 
 val origin : t
 val up : t