Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2.fluke 9/24/84; site vax2.fluke.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!fluke!kurt
From: kurt@fluke.UUCP (Kurt Guntheroth)
Newsgroups: net.lang
Subject: Re: Varieties of conditional statement
Message-ID: <964@vax2.fluke.UUCP>
Date: Thu, 10-Oct-85 11:09:54 EDT
Article-I.D.: vax2.964
Posted: Thu Oct 10 11:09:54 1985
Date-Received: Sat, 12-Oct-85 18:07:41 EDT
References: <418@phri.UUCP> <2600012@ccvaxa> <1901@reed.UUCP> <1703@peora.UUCP>
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 30

Mr. Roskos uses his own measure of what makes a language 'weaker' to
validate his basically religious argument that languages should be built
with pascal/c style conditional statements rather than ada 'comb' style 
statements.

There are other arguments.  For instance, the Pascal style if statement is
well known to result in ambiguities in the construction of reasonable
parsers.  (I believe there is a grossly complex mechanism that can be
applied to disambiguate the if statement; see SIMULA BEGIN by Birtwistle et.
al.)  One could argue on this basis that such languages are syntactically
weak, and thus that Ada style conditional constructs are superior.

Mr. Roskos also argues that having only one kind of block containing local
declarations is a property only of pascal style conditionals.  This is not
true, as it depends on the way block is defined in a language.  I also note
that the two blocks in an if-then-else statement will necessarily be
distinct under either style, so there is no clear superiority in this area
either.

I can't resist giving my own opinion here:  I like the Ada style 'comb'
structured statements.  The syntax is clean, and furthermore they result in
a more obvious cannonical indentation, making everybody's programs more
similar.  You can also define the list of statements enclosed in the parts
of a conditional or loop statement to be a block if the rest of your syntax
allows you to tell the difference between a declaration and a statement.

-- 
Kurt Guntheroth
John Fluke Mfg. Co., Inc.
{uw-beaver,decvax!microsof,ucbvax!lbl-csam,allegra,ssc-vax}!fluke!kurt