Thanks for the correction. I have to admit that I am ignorent of the GRT sort. I stared at the GRT sort for a while, and finally worked out what it's doing after sticking a print inside the map. I am writing down my finding on what is happenning inside a GRT sort here for the possible benefit to other monks.

@grt_sorted =
  map {substr $_ => $max_l}
  sort
  map {uc () . ("\0" x ($max_l - length)) . $_} @array;

[download]
The first map expands the original string with a 0 terminated string of width $max_l, concatinated with the original string itself. Eliminates the use of a slice in the Schwartzian sort.

The sort follows only sorts the first part of the string terminated at \0.

The second map then retrieves the original string with substr.

Very clever indeed. :-D

The tricky bit is the first map. I modified it to the following to inspect what's happenning inside the map -
map { my $c = uc () . ("\0" x ($max_l - length)) . $_;
      print "$_ => $c\n"; $c } @array;

[download]

In reply to Re: Re: noncase-sensitive sorting by Roger
in thread noncase-sensitive sorting by texuser74

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