From: "Christopher L Conway" <cconway@cs.nyu.edu>
To: "Sam Steingold" <sds@gnu.org>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] modifying hash tables
Date: Wed, 18 Jul 2007 12:00:57 -0400 [thread overview]
Message-ID: <4a051d930707180900r3b8b64b3pc8316ec0490ca8f7@mail.gmail.com> (raw)
In-Reply-To: <469E3171.7040205@gnu.org>
Assuming that your question is "is it OK to modify a Hashtbl while you
iterate over it?" and assuming that the answer is "maybe, but maybe
not" and assuming that I am looking for a way to avoid doing real
work, you might try the following:
(Hashtbl.fold
(fun key data f ->
(fun ht -> Hashtable.replace ht key (data+1); f ht))
ht
(fun _ -> ()))
ht
Chris
On 7/18/07, Sam Steingold <sds@gnu.org> wrote:
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> I want to modify the _current_ datum in Hashtable.iter, e.g., increment
> a count. Is this code valid?
> Hashtable.iter ht ~f:(fun ~key ~data ->
> Hashtable.replace ht ~key ~data:(data+1))
> (it appears to work, but I was told that "it is not guaranteed to work",
> i.e., the documentation does not promise that).
> If the above code is wrong, what is TRT?
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next prev parent reply other threads:[~2007-07-18 16:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-18 15:27 Sam Steingold
2007-07-18 16:00 ` Christopher L Conway [this message]
2007-07-18 16:01 ` Sam Steingold
2007-07-18 16:36 ` [Caml-list] " Brian Hurt
2007-07-18 16:08 ` [Caml-list] " David Allsopp
2007-07-18 16:38 ` Zheng Li
2007-07-18 20:38 ` [Caml-list] " Jon Harrop
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