[hcoop/debian/mlton.git] / basis-library / util / dynamic-wind.sml

(* Copyright (C) 1999-2006, 2008 Henry Cejtin, Matthew Fluet, Suresh
 *    Jagannathan, and Stephen Weeks.
 * Copyright (C) 1997-2000 NEC Research Institute.
 *
 * MLton is released under a BSD-style license.
 * See the file MLton-LICENSE for details.
 *)

structure DynamicWind: DYNAMIC_WIND =
struct

fun try (f: unit -> 'a, k: 'a -> 'b, h: exn -> 'b) =
   let
      datatype t =
         A of 'a
       | E of exn
   in
      case A (f ()) handle e => E e of
         A a => k a
       | E e => h e
   end

fun wind (thunk, cleanup: unit -> unit) =
   try (thunk, fn a => (cleanup (); a), fn e => (cleanup (); raise e))

end
Commit	Line	Data
7f918cf1 CE	1	(* Copyright (C) 1999-2006, 2008 Henry Cejtin, Matthew Fluet, Suresh
	2	* Jagannathan, and Stephen Weeks.
	3	* Copyright (C) 1997-2000 NEC Research Institute.
	4	*
	5	* MLton is released under a BSD-style license.
	6	* See the file MLton-LICENSE for details.
	7	*)
	8
	9	structure DynamicWind: DYNAMIC_WIND =
	10	struct
	11
	12	fun try (f: unit -> 'a, k: 'a -> 'b, h: exn -> 'b) =
	13	let
	14	datatype t =
	15	A of 'a
	16	\| E of exn
	17	in
	18	case A (f ()) handle e => E e of
	19	A a => k a
	20	\| E e => h e
	21	end
	22
	23	fun wind (thunk, cleanup: unit -> unit) =
	24	try (thunk, fn a => (cleanup (); a), fn e => (cleanup (); raise e))
	25
	26	end