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From: kurt@fluke.UUCP
Newsgroups: net.lang
Subject: Re: Discussion on removing punctuation in programming languages
Message-ID: <695@dragon.fluke.UUCP>
Date: Mon, 13-Oct-86 12:25:16 EDT
Article-I.D.: dragon.695
Posted: Mon Oct 13 12:25:16 1986
Date-Received: Tue, 14-Oct-86 07:14:27 EDT
Reply-To: kurt@dragon.UUCP (Kurt Guntheroth)
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 46

Reasons for continuing to have delimiters in languages:

1.  It makes error recovery easier/possible in the compiler.  
    Don't whine and snivel and say "if the compiler-writers were any good
    they could do adequate error recovery without noise tokens like
    delimiters."  That simply isn't true.  What have you gained if you have
    a language that is a tiny bit quicker to type in but the compiler can
    only mark the first syntax error, then gives up?  Making error recovery
    easier for the compiler improves its ability to find all your syntax
    errors in a single pass.
2.  Delimiters reduce the ambiguities in a grammar.
    This permits the compiler to use more expressive syntactic forms.  You
    can use more powerful forms if they can be separated and made distinct
    by delimiters.
3.  Delimiters reduce the tendency for the compiler to accept incorrect
    sentences as correctly formed syntax.
    I recently worked on a compiler that allowed function invocations using
    a named argument notation.  To invoke the function

	func (arg1, arg2, ... argN)

    You used the invocation

	func arg1 <exp1>, arg2 <exp2>, ... argN <expN>

    However, since expresions can also be function invocations you could
    have invocations like

	func1 arg11 func2 arg21 <exp21>

    To make a long story short, comments looked like

	! any characters following the "!" up to the end of the line.

    And if you accidentally forgot the "!", the resulting sentence
    frequently was accepted as a bizarre function invocation.  If the
    argument list had been delimited by "("...")", or the argument name and
    argument expression had been separated by ":=", this would have been
    avoided.  

    Noise words in languages add valuable redundancy that aids the human
    reader, compiler, and compiler writer.  I always think of the words
    spoken by C.A.R. Hoare in his 1983(?) Turing Lecture address, where he
    said approximately "Wouldn't it be wonderful if your Fairy Gotmother
    would wave her magic wand over your program and pronounce it correct,
    and all you had to do was type it in three times."