From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,448990452c132610 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-02-25 06:55:45 PST Path: archiver1.google.com!postnews1.google.com!not-for-mail From: dewar@gnat.com (Robert Dewar) Newsgroups: comp.lang.ada Subject: Re: The making of compilers Date: 25 Feb 2002 06:55:44 -0800 Organization: http://groups.google.com/ Message-ID: <5ee5b646.0202250655.6fd2bfb8@posting.google.com> References: NNTP-Posting-Host: 205.232.38.14 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: posting.google.com 1014648945 25799 127.0.0.1 (25 Feb 2002 14:55:45 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: 25 Feb 2002 14:55:45 GMT Xref: archiver1.google.com comp.lang.ada:20366 Date: 2002-02-25T14:55:45+00:00 List-Id: "tony gair" wrote in message news:... > After sticking my neck out and being shot out out of the sky by the big > guns..................................... > > I heard from a lecturer in 1990 that compilers were built > by writing a language subset compiler in assembler (or C > or C++ or.....) and then by using that subset to step by > step extend the language to its desired form. Yes, that's indeed the most reasonable approach if there are no existing compilers for the language. For example, Alsys Ada was initially implemented using a subset compiler written in PL/1. By the time GNAT was being created, the Alsys compiler already existed, and we first wrote in Ada 83, and bootstrapped using the Alsys compiler on a Sun, then once we were bootstrapped, we step by step extended, so that now we use quite a lot of Ada 95 features. > And he was really clever he was , he had glasses and a > beard and everything. I am not sure of the reason for this frivolous comment, but he was giving a perfectly reasonable account of how things are done. Your tone seems to indicate skepticism, but in this case I am afraid the skepticism comes from ignorance, and glasses-and-beard knew what he was talking about :-)