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|
type expr =
| EConst of int
| EAdd of expr * expr
[@@deriving visitors { variety = "iter" }]
let weight (e : expr) : int =
(* return the weight of an expr, where the weight of constants is its *)
(* value, and additions have weight 5. *)
let v = object
val mutable weight = 0
method weight = weight
inherit [_] iter as super
method! visit_EAdd env e0 e1 =
weight <- weight + 5;
super#visit_EAdd env e0 e1
method! visit_EConst env i =
weight <- weight + i;
super#visit_EConst env i
end in
v#visit_expr () e;
v#weight
;;
let c = EConst 2 in
let e = EAdd(c,EAdd(c,c)) in
print_int (weight e)
;;
|
