Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!willett!dwp
From: dwp@willett.UUCP (Doug Philips)
Newsgroups: comp.lang.misc
Subject: Re: Anyone want to design a language?
Message-ID: <554.UUL1.3#5129@willett.UUCP>
Date: 25 Feb 90 01:28:13 GMT
References: <6925@tekgvs.LABS.TEK.COM>
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 32

In <6925@tekgvs.LABS.TEK.COM>, toma@tekgvs.LABS.TEK.COM (Tom Almy) writes:
> Most postfix fanatics (typically Forth programmers, of which I am one) will
> say postfix is better than prefix (thinking of LISP) because it eliminates
> the need for all of those parenthesis. In fact, parenthesis (as grouping
> operators) are only needed if you don't know how many arguments are needed
> for a function. You can get rid of most parenthesis in a prefix language,
> for instance LOGO behaves much like a parenthesis-free LISP. The only
> real advantage of postfix is that it can be directly executed in a stack
> architecture.
There is another issue which is eval time.  In prefix languages you can
have the 'function' itself control when it evaluates its arguments.
The advantage to post-fix over pre-fix, for me, is that I find the
clutter of parens gets in my way.  It may be that I never stayed with
LISP long enough to chunk that kind of processing.

> What bothers me is not so much pre vs. in vs. post but what I call mixfix.
> Mixfix is a hodgepodge of pre/in/post fix notation that can be very
> confusing. At least LISP is consistantly prefix (LOGO isn't).
Yes, consistency is a big win.  It conflicts with extensibility.  Are you
really using an extensible language if you can't extend the syntax?

> Forth, the "king of postfix" uses prefix functions for string arguments.
PostScript does too, but perhaps in a more consistent way.  There is
no reason, a priori, that a Forth dialect can't be built which does this.
This kind of extensibilty is what makes Forth interesting to me.  However,
it is also easy to abuse.

		-Doug

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