flash@ee.qmc.ac.uk (Flash Sheridan) (06/07/88)
> Perhaps there are other "serious" lisp >systems available for the Mac or Mac II, Don't think so. There's ExperCommon[sic]Lisp in the more expensive version for the II. Can't afford it, and the version we have won't run on a II. But from experience with ECL on a Plus, avoid it. Speaking of XLIsp, has anybody patched it so it can cut&paste? From: flash@ee.qmc.ac.uk (Flash Sheridan) Reply-To: sheridan@nss.cs.ucl.ac.uk or_perhaps_Reply_to: flash@cs.qmc.ac.uk
psa@otter.hple.hp.com (Patrick Arnold) (06/13/88)
I would like to make it clear that I said that dynamic binding enables *some* forms of abstraction. Simon Brooke is wrong to say that to have abstraction you must have dynamic binding. There is a significant body of software engineering people who think that the black box notion of a procedure (function? I don't believe lisp has functions) is the only bona fide form of procedural abstractions. In my experience (a large Common Lisp program > 20k forms) we have used exclusivly lexical binding and found it to be no problem. When I posted the original note I got involved in a fierce argument with some of the other guys here (from the aforementioned body) who actually thought I'd posted an error. The outcome of this discussion was that the use of dynamic binding as an abstraction technique was probably only required in programs in which there is a great deal of local context (e.g. windowing systems). I personally think that lexical scoping is easier to use in most cases. Just because the black box notion of a procedure didn't originate in Lisp doesn't mean we shouldn't allow Lisps to incorporate these VERY IMPORTANT SOFTWARE ENGINEERING PRINCIPLES. Indeed I think tha case for using Lisp (actually I prefer pop) for serious software engineering becomes much stronger if we do (how many other languages have real first class procedures? Pascal definitely no, Modula2, Ada, C). Again I must emphasise that both types of binding are useful for certain tasks. It is important that neither of them is ABUSED because this results in trashy, difficult to maintain software and everyone knows there is far too much of that about. The problem is to educate the religious fanatics who are irrevocably attached to one particular form of binding away from blind assertions about which is best and towards discovering the relative strengths and weaknesses of either mechanisms. Patrick.