Path: utzoo!attcan!uunet!mcvax!cernvax!hjm
From: hjm@cernvax.UUCP (Hubert Matthews)
Newsgroups: comp.lang.forth
Subject: Re: Infix/Postfix notation
Keywords: infix, postfix, stacks
Message-ID: <816@cernvax.UUCP>
Date: 9 Sep 88 11:21:29 GMT
References: <2768@pt.cs.cmu.edu> <621@sas.UUCP>
Reply-To: hjm@cernvax.UUCP (Hubert Matthews)
Organization: CERN European Laboratory for Particle Physics, CH-1211 Geneva, Switzerland
Lines: 33


One of the other things about infix notation is that it works for two
parameter functions very easily, but three gets a bit tricky (you need
another symbol) and four starts to look kinda crazy.  For n parameters
you need n-1 symbols with infix; with prefix or postfix you need only
one.  Just try adding another argument to an infix function - it's messy!

If you do want infix notation for the if-then-else construct, then why not
use Hoare's notation:

a <| c |> b

where c is the test and a and b are the alternatives; true to the left
and false to the right.  It's just as well that boolean conditions can
have only two values or you would be stuck to extend this notation cleanly.
Or would you go to a four-way branch like this:

     x

     ^
     -

a <| c |> b

     _
     v

     y


Five is really tricky with a standard keyboard :-)

	Hubert Matthews