Path: utzoo!mnetor!uunet!mcvax!unido!ecrcvax!micha
From: micha@ecrcvax.UUCP (Micha Meier)
Newsgroups: comp.lang.prolog
Subject: Re: BSI Proposal
Message-ID: <517@ecrcvax.UUCP>
Date: 17 Mar 88 12:06:38 GMT
References: <229@gould.doc.ic.ac.uk> <771@cresswell.quintus.UUCP>
Reply-To: micha@ecrcvax.UUCP (Micha Meier)
Organization: ECRC, Munich 81, West Germany
Lines: 39

In article <771@cresswell.quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) writes:
>As Chris Moss says, most languages since Fortran regard blanks as
>significant.  Surely it is inconsistent to argue that
>	"RED O" and "REDO"
>are different, and that is a Good Thing, but
>	"red (O)" and "red(O)"
>being different is a Bad Thing?  Blanks are being treated as
>significant in both cases.  "RED O" and "red (" are both two tokens,
>and "REDO" and "red(" are both one token; it's exactly the same thing.
>What's sauce for the goose is sauce for the gander.

	I'm no fan of the allowed space between the functor and
	the opening parenthesis, but this does not seem to me as
	a good argument. In the usual languages blankspaces are
	allowed between characters of different classes (in the POP
	meaning of character classes), with some exceptions like
	e.g. the floating point constants. From this point of view
	a space between "red" and "(" seems rather natural,
	to say that "red(" is one token seems to me at least arguable
	(easy to implement, I admit).

	But there are other consequences of this BSI rule - is there any
	reasonable argument to forbid binary operators that start with
	a capital letter or that contain letters and graphic chars?

	Actually, we have implemented the BSI standard in our Sepia,
	(it's probably one of the first implementations)
	but I have to admit that one of the first things to provide
	was a switch to be able to switch it off. There is a long list
	of problems we have encountered, we are going to pass them to
	BSI soon. I have appreciated to have a minimal list of
	built-ins provided by BSI, but the description contains so
	many errors that one has really to take care when implementing
	them. My global impression from BSI is, I'm afraid, close
	to that of R.A.O'K, it is a new language, and very
	difficult to implement. I've never really understood the grammar
	and the 'Formal Specification of Prolog', though :-)

--Micha