Re: [FWP] Turing machine simulator

[robin@kitsite.com]

On Fri, Dec 08, 2000 at 04:15:21AM -0500, Mark Rogaski wrote:
> In a fit of insomnia, I worked up a simulation of a simple one head, one
> R/W tape, deterministic Turing machine.  The rules for it are as such:

Coolness! I was inspired to write my own version, which differs
mainly in the syntax of the input file.

Each rule is five characters, in the same order as Mark's.
The state is an ascii character not a number, and the halt
state is "!". Initial state is "A".

So Mark's example program would be

A1A1R
A0A0R
A B L
B1B0L
B0C1L
B C1L
C1C1L
C0C0L
C ! R


I was aiming for brevity, and it *is* 58 characters shorter than
Mark's version. I'm sure it could be compressed more, with some
thought.

 .robin.


#!/usr/local/bin/perl -p0777
y= =\0=;s=(.)(.)(.)(.)(.)="s/(.)\Q$1\E\b\Q$2\E/".($5eq"R"?"\${1}$4$3\b":
"$3\b\${1}$4")."/&¨"=eg;$t=$_;$_="A\b".shift;{$_="\0$_\0";eval$t;
$@||die;/!\ch/&&last;redo}

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