Yes, but so can YAPE::Regex::Explain.

#!/usr/bin/perl
use warnings;
use strict;

use YAPE::Regex::Explain;

print YAPE::Regex::Explain->new('^[0-9]+$')->explain();
print "\n\n";
print YAPE::Regex::Explain->new('^\S{11,}$')->explain();

__END__
The regular expression:

(?-imsx:^[0-9]+$)

matches as follows:
  
NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  [0-9]+                   any character of: '0' to '9' (1 or more
                           times (matching the most amount possible))
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------


The regular expression:

(?-imsx:^\S{11,}$)

matches as follows:
  
NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  \S{11,}                  non-whitespace (all but \n, \r, \t, \f,
                           and " ") (at least 11 times (matching the
                           most amount possible))
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
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-stevieb