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From: wmb@MITCH.ENG.SUN.COM
Newsgroups: comp.lang.forth
Subject: Re: Use explicit arguments
Message-ID: <9102050318.AA12062@ucbvax.Berkeley.EDU>
Date: 5 Feb 91 02:15:49 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: wmb%MITCH.ENG.SUN.COM@SCFVM.GSFC.NASA.GOV
Organization: The Internet
Lines: 34

> : DOTS  ( a \ n -- )  FOR  @+ .  NEXT  DROP ;
>
>  instead of any of:
>
> : DOTS  ( a \ n -- )  0 ?DO  DUP @ .  CELL +  LOOP ;
> : DOTS  ( a \ n -- )  0 ?DO  DUP I CELL * + @ .  LOOP ;
> : DOTS  ( a \ n -- )  CELL *  OVER + SWAP  ?DO  I @ .  CELL +LOOP ;

How about:

        : DOTS  ( a \ n -- )  0 ?DO  @+ .  LOOP  DROP  ;

It should be easy for the compiler to figure out that it can do the
optimization.  Chuck wasted a lot of people's time when he introduced
a new function to handle a special case of an existing construct, rather
than make his compiler a little smarter.  The compiler optimization would
have made everybody's existing code run faster, rather than making everybody
rewrite their code, which then would be incompatible with systems without
FOR .. NEXT .

Admittedly, DO .. LOOP is a bit of a crock, but it is a crock with a lot
of history behind it, and it does in fact work.


> I assume the stack diagram for @+ ( a -- a+ \ n ).  These incrementing fetch
> words are some of the newer "ideas" injected into the Forth domain by Chuck.
> He's had a chance to see what Forth really looks like in hardware.

Of course, C has had autoincrementing pointers for 20 years.  In Forth,
a new idea is when Chuck reinvents or finally decides to use something
that has been around since the dawn of time.  Then everybody decides that,
if Chuck says it, it must be right.

Mitch Bradley, wmb@Eng.Sun.COM