sub dictcmp
{
   my $ac = $a;
   my $bc = $b;
   while( 1 ) {
      my @a = $ac =~ /^\s*(([A-Za-z]+)|(\d+))(.*)/;
      my @b = $bc =~ /^\s*(([A-Za-z]+)|(\d+))(.*)/;
      return 0 if !defined $a[0] & !defined $b[0];
      return -1 if !defined $a[0];
      return 1 if !defined $b[0];
      my $res;
      if( $a[0] =~ /\d+/ && $b[0] =~ /\d+/) {
         $res = $a[0] <=> $b[0];
      }
      else {
         $res = $a[0] cmp $b[0];
      }
      return $res if $res;
      $ac = $a[3];
      $bc = $b[3];
   }
}

##</code><code>##

my @list = ( "x10 y", "1abc", "a10y", "x9y", " b1" );
print join "\n", sort dictcmp @list;

##</code><code>##

1abc
a10y
 b1
x9y
x10 y