Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!border2.nntp.dca1.giganews.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!news.iecc.com!.POSTED!nerds-end From: wclodius@earthlink.net (William Clodius) Newsgroups: comp.compilers Subject: Re: executable semantics, was Formatting of Language LRMs Date: Fri, 4 Jul 2014 15:53:01 -0600 Organization: Compilers Central Lines: 22 Sender: news@iecc.com Approved: comp.compilers@iecc.com Message-ID: <14-07-014@comp.compilers> References: <14-06-010@comp.compilers> <14-06-016@comp.compilers> <14-06-021@comp.compilers> <14-07-004@comp.compilers> <14-07-009@comp.compilers> NNTP-Posting-Host: news.iecc.com X-Trace: miucha.iecc.com 1404687990 11357 2001:470:1f07:1126:0:676f:7373:6970 (6 Jul 2014 23:06:30 GMT) X-Complaints-To: abuse@iecc.com NNTP-Posting-Date: Sun, 6 Jul 2014 23:06:30 +0000 (UTC) Keywords: semantics Posted-Date: 06 Jul 2014 19:06:30 EDT X-submission-address: compilers@iecc.com X-moderator-address: compilers-request@iecc.com X-FAQ-and-archives: http://compilers.iecc.com Xref: csiph.com comp.compilers:1304 Ivan Godard wrote: > How would it differ from a document containing, > > say, Java? > > If the document were a compiler written in Java (i.e. a recognizer and > checker) then formally there is no difference. Practically, an immense > difference. VWG is an ASL for specifying languages. All of Algol68 in > VWG was about four pages of appendix; a compiler for Algol68 written in > Java would be much more than that, even after you strip out optimization > and code generation. > > Also, the specification in VWG lends itself to use of metatools: make a > change to the grammar and verify that the revision is complete, > consistent and not redundant. Not something easy to do when the language > is expressed by a Java recognizer. FWIW if I remember correctly a varient of that belief led the Modula II standard to attempt to descibe the langauage using the Vienna Definition Method. They hoped to verify the formal description automatically, but they could not afford the commercial tools and the implementation of one of the participants was not ready in time when they decided they had to get it out the door.