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(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* The OCaml programmers *)
(* *)
(* Copyright 2018 Institut National de Recherche en Informatique et *)
(* en Automatique. *)
(* *)
(* All rights reserved. This file is distributed under the terms of *)
(* the GNU Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
(** Function manipulation.
@since 4.08 *)
(** {1:combinators Combinators} *)
external id : 'a -> 'a = "%identity"
(** [id] is the identity function. For any argument [x], [id x] is [x]. *)
val const : 'a -> (_ -> 'a)
(** [const c] is a function that always returns the value [c]. For any
argument [x], [(const c) x] is [c]. *)
val flip : ('a -> 'b -> 'c) -> ('b -> 'a -> 'c)
(** [flip f] reverses the argument order of the binary function
[f]. For any arguments [x] and [y], [(flip f) x y] is [f y x]. *)
val negate : ('a -> bool) -> ('a -> bool)
(** [negate p] is the negation of the predicate function [p]. For any
argument [x], [(negate p) x] is [not (p x)]. *)
(** {1:exception Exception handling} *)
val protect : finally:(unit -> unit) -> (unit -> 'a) -> 'a
(** [protect ~finally work] invokes [work ()] and then [finally ()]
before [work ()] returns with its value or an exception. In the
latter case the exception is re-raised after [finally ()]. If
[finally ()] raises an exception, then the exception
{!Finally_raised} is raised instead.
[protect] can be used to enforce local invariants whether [work ()]
returns normally or raises an exception. However, it does not
protect against unexpected exceptions raised inside [finally ()]
such as {!Stdlib.Out_of_memory}, {!Stdlib.Stack_overflow}, or
asynchronous exceptions raised by signal handlers
(e.g. {!Sys.Break}).
Note: It is a {e programming error} if other kinds of exceptions
are raised by [finally], as any exception raised in [work ()] will
be lost in the event of a {!Finally_raised} exception. Therefore,
one should make sure to handle those inside the finally. *)
exception Finally_raised of exn
(** [Finally_raised exn] is raised by [protect ~finally work] when
[finally] raises an exception [exn]. This exception denotes either
an unexpected exception or a programming error. As a general rule,
one should not catch a [Finally_raised] exception except as part of
a catch-all handler. *)
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