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From: gateley@m2.csc.ti.com (John Gateley)
Newsgroups: comp.lang.misc
Subject: Re: PL/I Grammar
Keywords: PL/I, C, grammar, parser
Message-ID: <94987@ti-csl.csc.ti.com>
Date: 19 Oct 89 17:56:02 GMT
References: <2956@usceast.UUCP> <1989Oct18.012237.548@esegue.segue.boston.ma.us>
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Reply-To: gateley@m2.UUCP (John Gateley)
Organization: TI Computer Science Center, Dallas
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In article <1989Oct18.012237.548@esegue.segue.boston.ma.us> johnl@esegue.segue.boston.ma.us (John R. Levine) writes:
>The semantics [of PL/I] are messy, too.  Consider:
>	A = B = C;
>which compares B and C and sets A to '1'B if they are equal.


Minor nit: this is not messy semantics, this is still messy syntax.
Consider the Lisp version of the above statement (which is pretty
close to an abstract syntax tree):

(setq a (= b c))

The semantics are perfectly clear, it is the syntactic overloading of '='
which makes the above statement messy. (I know my Lisp version doesn't
correspond exactly, but the ``correct version'' is more complex and doesn't
add anything to the discussion).

John
gateley@m2.csc.ti.com