From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from weis@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id JAA08253 for caml-redistribution; Thu, 28 Jan 1999 09:20:03 +0100 (MET)
Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id GAA11303 for <caml-list@pauillac.inria.fr>; Thu, 28 Jan 1999 06:08:30 +0100 (MET)
Received: from linc.cis.upenn.edu (LINC.CIS.UPENN.EDU [158.130.12.3])
	by nez-perce.inria.fr (8.8.7/8.8.7) with ESMTP id GAA04583
	for <caml-list@inria.fr>; Thu, 28 Jan 1999 06:08:27 +0100 (MET)
Received: from codex.cis.upenn.edu (CODEX.CIS.UPENN.EDU [158.130.6.15])
	by linc.cis.upenn.edu (8.8.5/8.8.5) with ESMTP id AAA09783
	for <caml-list@inria.fr>; Thu, 28 Jan 1999 00:08:25 -0500 (EST)
Received: (from mwh@localhost)
	by codex.cis.upenn.edu (8.8.5/8.8.5) id AAA21644
	for caml-list@inria.fr; Thu, 28 Jan 1999 00:08:24 -0500 (EST)
From: Michael Hicks <mwh@dsl.cis.upenn.edu>
Message-Id: <199901280508.AAA21644@codex.cis.upenn.edu>
Subject: one-time initialization
To: caml-list@inria.fr
Date: Thu, 28 Jan 1999 00:08:23 -0500 (EST)
X-Mailer: ELM [version 2.4 PL23-upenn3.1]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: weis

I wonder if anyone knows how to optimize the following (simplified for the
sake of dicussion) situation:

let global = ref None
let init i =
  global := Some i
let f () =
  match (!global) with
    Some x -> x
  | None -> failwith "not initialized";;
let g() =
  match (!global) with
    ...

Essentially, there is some global state that is initialized once, and is
used by all functions in the module.  In a more realistic situation, this
state might be initialized by reading in a file.  Given that following
initialization the global state never changes, it should be conceivable to
eliminate the match and dereference; on my machine (pentium 166), the match
and dereference result in about a 30% slowdown.  I've fooled around with
some things, but haven't found anything that performs better than this
straightforward approach or is any more elegant.

Thanks,
Mike
-- 
Michael Hicks
Ph.D. Candidate, the University of Pennsylvania
http://www.cis.upenn.edu/~mwh            mailto://mwh@dsl.cis.upenn.edu
"I worked with an individual who plugged his power strip back into itself
and for the life of him could not understand why his computer would not
turn on."