Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!SUN.COM!wmb
From: wmb@SUN.COM
Newsgroups: comp.lang.forth
Subject: Re: Shortest selfreproducing Forth program
Message-ID: <9001180238.AA28699@jade.berkeley.edu>
Date: 17 Jan 90 22:24:07 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: Forth Interest Group International List <FIGI-L%SCFVM.bitnet@jade.berkeley.edu>
Organization: The Internet
Lines: 47

> That makes yours 13 chars to be completely self-reproducing when run, since
> running it also generates the `ok'.

I don't count the "ok" prompt as part of the output.


> Are interactive input lines really programs?

Sure, why not?  Forth doesn't make a big distinction between
interactive commands and programs, as do other languages.
This is one of the great things about Forth, and it seems like
fair game to be able to use it.  Admittedly, however, whoever first
posed this problem (it was floating around the net several years
ago) probably wasn't thinking about Forth's incremental compilation
model.


> : de recursive ' de (see) ;
>
> which looks like it should work and doesn't?

Several problems:

1) use ['] instead of '
2) (see) is not standard Forth
3) The decompiler probably won't regenerate the "recursive" keyword

On my system, you can get close with this technique:

 : de recursive
    ['] de (see)
 ;

results in:

 : de
    ['] de (see)
 ;

but, anyway, using the decompiler is not the right approach because
of objection (2)


There is probably some other way to solve this problem, but I haven't
thought of it yet.

Mitch