use Text::WagnerFischer "distance";
use List::Util 'min';

my $a="abbaba";
my $b="ababbba";
my $limit= 3;

my $n= 0;
my $max= min(length $a, length $b);
++$n while $n < $max
        && distance(substr($a,-$n-1), substr($b,0,$n+1)) < $limit;

if ($n) {
  printf "'%s' matches '%s' with edit distance %d",
    substr($a,-$n), substr($b,0,$n),
    distance(substr($a,-$n), substr($b,0,$n))
}