What this obfu lacks in artistic merit (that's supposed to be a Möbius strip), I think it makes up in technique and name. I got the idea from a Haskell assignment (egads! Posting homework to the monastery?), and I think the main concept is mildly clever. I'd love to talk about it, but I don't want to spoil the surprise!
#! /usr/bin/perl -w
use strict;
sub godel{my ($f,$a,$l)=@_;return $a unless @$l;my$x=shift @$l;&$f(
$x,&godel($f,$a,$l));}my @M=split '', "Just another ";my @I =split '',
"Perl hacker,"; my @U =reverse @M; sub
escher{my ($l,$m) =@_;sub{$l= pop @U
if @U;$l.&$m();} } unshift@U, split ''
,"pool egnarts";my$bach=&godel(\&escher,&godel(\&escher,sub{return"\n"}
,\@I),\@M);print &$bach(); ### Inspired by Douglas Hofstadter's _GEB_
Tested on Perl 5.6.1, Linux 2.4.18.
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Found a typo in this node? /msg me
% man 3 strfry
Nice. Reading this was like comfort food.
There's a spoiler in the readmore.
- Fill @M with "Just another "
- Fill more with "strange loop"
- Nested godels on the stack while the global @U has data so the "Perl hacker," portion is just overwritten during $l = of escher(). Here \@I is just an iterator (though it contains some tantalizingly familiar data) so that @U can be popped properly.
P( e( r( l( ( h( a( c( k( r( ,( "\n" ) ) ) ) ) ) ) ) ) ) ) - Pretend to do something with @M though really this is just another loop to go extract more stuff from the global @U.
J( u( s( t( ( a( n( o( t( h( e( r( "strange loop" ) ) ) ) ) ) ) ) ) ) ) )
#! /usr/bin/perl -w
use strict;
use vars qw( @U );
my @M = split '', "Just another ";
my @I =split '', "Perl hacker,";
@U = reverse @M;
unshift( @U,
split '',
"pool egnarts" );
print godel( godel( sub{ "\n" },
\ @I ),
\ @M )->();
sub godel
{
my ($a, $l) = @_;
return $a unless @$l;
my $x = shift @$l;
return escher( $x,
godel( $a, $l ) ) ;
}
sub escher
{
my ($l, $m) = @_;
return
sub
{
$l = pop @U if @U;
return $l . $m->();
};
}
Nice summary! (readmore is spoily)
You missed a subtlety about godel, though. What it's actually doing is nesting anonymous calls to the sub returned by escher, which do the extraction from @U. The whole thing returns a sub, which calls more subs nested in the closure, and so on, and so on; that's the part I think is cool.
godel is equivalent to foldr in Language::Functional (or Haskell, for that matter); escher is the combining function, and sub {"\n"} is the start value.
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Found a typo in this node? /msg me
% man 3 strfry
Oh well yeah, each recursive godel() generates another function via escher() which has a bit more of the overall string. I sort of implied that in the stack.
So if perl were Haskell, what else would you have here?