Return-Path: Delivery-Date: Received: from leopard.cs.byu.edu (no rfc931) by swan.cl.cam.ac.uk with SMTP (PP-6.5) outside ac.uk; Fri, 6 Jan 1995 15:43:13 +0000 Received: by leopard.cs.byu.edu (1.38.193.4/16.2) id AA02100; Fri, 6 Jan 1995 08:38:14 -0700 Sender: info-hol-request@lal.cs.byu.edu Errors-To: info-hol-request@lal.cs.byu.edu Precedence: bulk Received: from crl.dec.com by leopard.cs.byu.edu with SMTP (1.38.193.4/16.2) id AA02096; Fri, 6 Jan 1995 08:38:11 -0700 Received: by crl.dec.com; id AA24734; Fri, 6 Jan 95 10:31:09 -0500 Received: by easynet.crl.dec.com; id AA26201; Fri, 6 Jan 95 10:24:54 -0500 Message-Id: <9501061524.AA26201@easynet.crl.dec.com> Received: from ricks.enet; by crl.enet; Fri, 6 Jan 95 10:31:08 EST Date: Fri, 6 Jan 95 10:31:08 EST From: "Tim Leonard, DTN 225-5809, HLO2-3/C11" To: info-hol@leopard.cs.byu.edu Apparently-To: info-hol@leopard.cs.byu.edu Subject: Re: Difficulties with large terms David Shepherd says: Basically, what is need is not an exact "=" function but a "fast approximation" which only returns true if the terms are equal but may return false negatives if it can't quickly determine equality. Since ML has exceptions, you might alternatively define your fast equal to return a boolean quickly, or fail. It can be useful to have a "fast or fail" form of all sorts of things, not just equality tests. It's a way of defining caches, for example.