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|
(* TEST
*)
open Effect
open Effect.Shallow
type _ t += Get : int t
| Set : int -> unit t
| Print : string -> unit t
let handle_state init f x =
let rec loop : type a r. int -> (a, r) continuation -> a -> r * int =
fun state k x ->
continue_with k x
{ retc = (fun result -> result, state);
exnc = (fun e -> raise e);
effc = (fun (type b) (eff : b t) ->
match eff with
| Get -> Some (fun (k : (b,r) continuation) ->
loop state k state)
| Set new_state -> Some (fun (k : (b,r) continuation) ->
loop new_state k ())
| e -> None) }
in
loop init (fiber f) x
let handle_print f =
let rec loop : type r. (unit, r) continuation -> r =
fun k ->
continue_with k ()
{ retc = (fun x -> x);
exnc = (fun e -> raise e);
effc = (fun (type a) (eff : a t) ->
match eff with
| Print s -> Some (fun (k : (a,r) continuation) ->
print_string s; loop k)
| e -> None) }
in
loop (fiber f)
let comp () =
perform (Print (Printf.sprintf "Initial state: %d\n" (perform Get)));
perform (Set 42);
perform (Print (Printf.sprintf "Updated state: %d\n" (perform Get)));
perform (Set 43)
let main () =
let (), i = handle_print (handle_state 0 comp) in
Printf.printf "Final state: %d\n" i
let _ = main ()
|
