From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-0.5 required=3.0 tests=BAYES_05,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.5-pre1 X-Received: by 2002:a37:4484:: with SMTP id r126mr30848574qka.18.1622710109364; Thu, 03 Jun 2021 01:48:29 -0700 (PDT) X-Received: by 2002:a25:db13:: with SMTP id g19mr48478291ybf.462.1622710109188; Thu, 03 Jun 2021 01:48:29 -0700 (PDT) Path: eternal-september.org!reader02.eternal-september.org!news.dns-netz.com!news.freedyn.net!newsfeed.xs4all.nl!newsfeed8.news.xs4all.nl!tr1.eu1.usenetexpress.com!feeder.usenetexpress.com!tr3.iad1.usenetexpress.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Thu, 3 Jun 2021 01:48:29 -0700 (PDT) In-Reply-To: <87bl8qf2wt.fsf@nightsong.com> Injection-Info: google-groups.googlegroups.com; posting-host=202.67.103.232; posting-account=S_MdrwoAAAD7T2pxG2e393dk6y0tc0Le NNTP-Posting-Host: 202.67.103.232 References: <87bl8qf2wt.fsf@nightsong.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <05793348-cd9c-4967-8868-07f9c5ae63f7n@googlegroups.com> Subject: Re: Proliferation of Reserved Words From: Robin Vowels Injection-Date: Thu, 03 Jun 2021 08:48:29 +0000 Content-Type: text/plain; charset="UTF-8" Xref: reader02.eternal-september.org comp.lang.ada:62107 List-Id: On Tuesday, June 1, 2021 at 5:40:53 PM UTC+10, Paul Rubin wrote: > "Randy Brukardt" writes: > > At least twice it was proposed that Ada have "keywords", identifiers with > > special meaning in the syntax but that were not reserved. . > I remember this as a fundamental decision of PL/I that made PL/I quite > hard to parse using the automata-based methods developed not long > afterwards. I don't know what consequences that had for PL/I or > anything else, if any. But I think it was retrospectively considered a > mistake. . It was definitely never considered a mistake in PL/I. Not having reserved words means that you do not have to steer clear of using any particular words when you design a program. It also means that a program will continue to compile even when new keywords are introduced into the language. Over the years, new keywords were introduced into PL/I, without invalidating existing programs. . Reserved words are the bane of COBOL. . > It's a lot easier to separate parsing and scanning if you can > have reserved words. > > OTOH I know that C compilers sometimes (usually?) handle typedefs by > having the parser tell the scanner to treat the typedef name as > keyword-like, after it sees that a typedef has been defined.