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|
open Ppx_hash_lib.Std
open Hash.Builtin
module Barbins_example = struct
module X = struct
type t = int [@@deriving hash]
end
module Y = struct
type y = int [@@deriving hash]
end
module Z = struct
type t = int [@@deriving hash]
end
module Example = struct
module T = struct
type t =
{ x : X.t
; y : Y.y
; z : Z.t
; mutable cached : int option [@hash.ignore]
}
[@@deriving hash]
end
module T_type = struct
type t = T.t =
{ x : X.t
; y : Y.y
; z : Z.t
; mutable cached : int option
}
end
module Unmemoized = T
module Memoized = struct
include T_type
let hash t =
match t.cached with
| Some x -> x
| None ->
let cached = T.hash t in
(* dont use state *)
t.cached <- Some cached;
cached
;;
let hash_fold_t (state : Hash.state) (t : t) = hash_fold_int state (hash t)
(* use state *)
end
end
module Client = struct
(* ensure overrides are typed correctly *)
type t1 = Example.Unmemoized.t [@@deriving hash]
type t3 = Example.Memoized.t [@@deriving hash]
end
end
|
