Subject: Re: CL grammar ambiguities? From: Erik Naggum <email@example.com> Date: 17 Feb 1995 18:58:51 UT Newsgroups: comp.lang.lisp Message-ID: <19950217T185851Z.firstname.lastname@example.org> [Jeff Dalton] | Of course one can have a standard without absolute precision! | Whatever gave you the idea that one couldn't? wearing my standards-committee member and standards writer hat for a second or two (it hurts to wear it), a standard with absolute precision must be about things for which absolute precision makes sense, such as dimensions of physical objects such as those for mechanical and electrical engineering. however, even they will not enumerate everything that will go wrong if you do something that is outside of the scope of the standard. defining the scope of a standard is the hardest part of the process, because it defines what you will and will not talk about. the Lisp reader as defined does not detail what will happen to any random character sequences when presented to it as input, but rather what should be presented as input to that reader when a particular set of results is expected and desired. I think this is no different from any other syntax description, formal or informal. | Indeed, can anyone think of a programming language standard that does | have absolute precision? modula-2 comes close. its formal semantics is defined using VDM. I also think Scheme comes close for its semantics. this hinges on an operational definition of "absolute precision" that makes it possible for the this term to make sense, and I don't think we have an absolutely precise definition of "absolute precision" against which anything could be measured. #<Erik> -- miracle of miracles. look what the Net dragged in.