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From: cik@l.cc.purdue.edu (Herman Rubin)
Newsgroups: comp.lang.misc
Subject: Re: Anyone want to design a language?
Summary: Comprehensibility, communicability, and "how the operations
	 are done" are different
Message-ID: <1968@l.cc.purdue.edu>
Date: 27 Feb 90 14:31:53 GMT
References: <10979@saturn.ADS.COM> <1106@thor.wright.EDU>
Organization: Purdue University Statistics Department
Lines: 41

In article <1106@thor.wright.EDU>, econrad@thor.wright.edu (Eric Conrad) writes:
> From article <10979@saturn.ADS.COM>, by xanthian@saturn.ADS.COM (Metafont Consultant Account):
> > Better, make the language strictly postfix, give it exactly one
>                                      ^^^^^^^
> 
> Why not prefix notation?  Prefix notation is more common than postfix
> in mathematical literature,
> 	f(x,y,z) rather than (x,y,z)f
> I suspect that it is a easier to read for those of us used to reading
> from left to right since it emphasizes the operators rather than the
> operands.
> 
> Of course I haven't used an HP calculator in a long time so I am
> probably prejudiced.

Mathematical notation is mostly a mixture of prefix and infix notation,
with infix predominating in use.  There are syntactic advantages to
prefix and postfix (lack of parentheses), although additional separator
characters may be needed.  If we had started out with a strictly prefix
(Polish notation) or a strictly suffix (reverse Polish), by all means
we would design our computer languages accordingly.  However, there are
situations where infix notation is easier to understand.

When it comes to carrying out a calculation which is not inlined, how is
this done?  The normal procedure is to create the argument list (this is
done in various ways) and then to call the procedure.  Thus, computation
seems to be essentially postfix.  This is even true with simpler situations
on calculators, and for hand calculation.  When an arithmetic operation is
performed, the arguments are normally assembled before the operation is
begun.  This is why I find RP calculators easier to use, besides being less
error prone (someone came into the office when I was making an entry; did I
hit the + key or not?).

The aim of the language is for the human, not the computer, to have the
easy time.  This means that the language should be able to communicate
to the compiler what the human wants done, and this should not be restricted
to what the compiler-writer thinks the human might want done.
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet, UUCP)