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To: Max Kirillov <max630@mail.ru>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] static variables in a function
References: <20020614170830.28193.qmail@web10705.mail.yahoo.com>
	<vfiznxxagiy.fsf@harp.is.s.u-tokyo.ac.jp>
	<20020615114201.B1425@max.home>
From: John Prevost <j.prevost@cs.cmu.edu>
Date: 15 Jun 2002 02:36:03 -0400
In-Reply-To: <20020615114201.B1425@max.home>
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>>>>> "mk" == Max Kirillov <max630@mail.ru> writes:

    mk> Hello.  The code you write will generate a new (empty) ref at
    mk> every call.

Actually, it won't.  Take a look at the code that was sent by Yutaka OIWA:

let get_chunk =
  let chunks_list = ref [] in
  fun () ->
    ...

The ref is bound outside of the function definition, so it's created
once and kept in the closure, not allocated in each call.  If it were
written this way:

let get_chunk () =
  let chunks_list = ref [] in
  ...

or equivalently:

let get_chunk =
  fun () ->
    let chunks_list = ref [] in
    ...

it would be created separately for each call.  But the way it was
originally written is correct.

Your version also works, but creates a module-level binding for the
value as well, which isn't desirable for something like this, where
you want the value to be local to the function definition.

John.

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