Do you know LISP? It's pretty easy to translate into Perl:

#!/usr/bin/perl -w
use strict;

*prev = sub { 
    my $a = $_[0] || 0;
    sub { $a };
};

*fib = sub {
    ($a, $b) = ($_[0] + $_[1]->(), $_[0]);
    printf "%d$/", $a;
    $_ = sub { fib( $a, prev($b) ) };
};

print "$_$/" for ++$|;
fib(1, prev(0)); 
for my $var (1 .. shift || 10) {
    $_->();
}
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Alright, that's not necessary *good* LISP, but you should have no trouble deciphering the algorithm without extraneous parenthesis. ©