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To: caml-list@inria.fr
Subject: [Caml-list] where is my count: newbie's question
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Date: Mon, 11 Jun 2001 12:21:00 +0200
From: Francois Thomasset <Francois.Thomasset@inria.fr>
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Sorry if this is a naive question, but I can't make out the reason of the 
behavior of the following function, which is a (seemingly!) slighty 
modification of the gensym example:
# let fnx(x) = let count = ref 0 in         
  let f() =                                 
  Printf.printf "x = %d\n" x;
  Printf.printf "count = %d\n" !count;
  count := !count + 1; !count
  in f;;
val fnx : int -> unit -> int = <fun>
I would have expected that count remembers its previous value, which would be 
incremented at each call, but this is not true : !count is always 0.
Of course if I remove the int argument I retrieve the behavior I expected:
# let fnx = let count = ref 0 in
  let f() =
  Printf.printf "count = %d\n" !count;
  count := !count + 1; !count
  in f;;
val fnx : unit -> int = <fun>
# fnx();;
count = 0
- : int = 1
# fnx();;
count = 1
- : int = 2



					François Thomasset.
					INRIA (A3)

Tel: +33 (1) 39-63-54-75
Fax: +33 (1) 39-63-53-30 ou +33 (1) 39-63-59-95
Email: Francois.Thomasset@inria.fr
Smail: INRIA, Rocquencourt, BP 105, 78153 Le Chesnay Cedex, France


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