Re: [NOISE] Curly braces [was Re: Curl]

[Bruce Lewis <address@hidden>]

Morgan McGuire <morgan3d@yahoo.com> writes:

> That's because you write compilers, not geometry code.  The main
> motivation for adding infix to Curl was the graphics guys getting
> killed trying to debug math like:
> 
> {if {> {/ {+ {- b} {sqrt {- {* b b} {* 4 a c}}}} {* 2 a} 0}
>    'positive-root
>    'negative-root}

They didn't have an auto-indent editor to work in?  That would have
uncovered the missing close brace after {* 2 a} in no time.

Of course, I'm sure the graphics guys would have found the problem in
the following expression at a glance, right?

-b+sqrt(b*b-4*a*c)/2*a > 0 ? "positive-root" : "negative-root"

I do think infix syntax can be helpful, especially once you're used to
the precedence rules.  But the problems with prefix syntax are generally
overblown.  A little indentation goes a long way.

(if (positive? (/ (+ (- b)
		     (sqrt (- (* b b)
			      (* 4 a c))))
		  (* 2 a)))
    'positive-root
    'negative-root)

In fact, this example gives division the same kind of prominence it has
as customarily written on paper.

Infix almost always makes it easier to transcribe a math formula into a
computer program, but relative ease of readability/debugging/
understanding is debatable. IMO.

-- 
<brlewis@[(if (brl-related? message)    ; Bruce R. Lewis
              "users.sourceforge.net"   ; http://brl.sourceforge.net/
              "alum.mit.edu")]>