Re: what most every language is missing :-)

[Guy Steele - Sun Microsystems Labs <address@hidden>]

   Date: Thu, 27 Mar 2003 11:31:44 -0600
   From: Trevis Rothwell <tjr@acm.org>
   To: ll1-discuss@ai.mit.edu
   Subject: what most every language is missing  :-)
   
   
   How about adding a "might-equal" operator?  I recommend useng the
   characters "=?".  I hav implemented my hone programming language,
   incubating the might-equal operater.  It works somthing like this:
   
     if (x =? y)
       print ("x might equal y");
     else
       print ("x might not equal y");
   
   Acording to my studys, the might-eqqul operatir is 299834% more
   useful than the standerd ekwal operator.  For testing porposes, I
   have usd the mighty-kwal operatyr in severul custom sofware
   packages, including spell chex and statistics soffy-soff.  I hope
   that you ull can make yous of it in yore own pergroomink lunkishes.
   
   :-)

It's dangerous to make jokes about programming languages:
almost every parody feature you can think of has already
been tried out seriously.

In this case, for interval arithmetic, where a numerical
quantity is represented by a lower and upper bound for
a segment of the real number line that contains the
quantity of interest, sometimes the best you can do
is ask whether "x possibly equals y".  Sun Fortran supports
interval arithmetic and provides 12 comparison operators:

	x .CLT. y	certainly(x .LT. y)
	x .CLE. y	certainly(x .LE. y)
	x .CEQ. y	certainly(x .EQ. y)
	x .CGE. y	certainly(x .GE. y)
	x .CGT. y	certainly(x .GT. y)
	x .CNE. y	certainly(x .NE. y)

	x .PLT. y	possibly(x .LT. y)
	x .PLE. y	possibly(x .LE. y)
	x .PEQ. y	possibly(x .EQ. y)
	x .PGE. y	possibly(x .GE. y)
	x .PGT. y	possibly(x .GT. y)
	x .PNE. y	possibly(x .NE. y)

"I am not making this up."  This is actually useful.

--Guy Steele