G'day cavac,

Sorry for the slow response: I've been unwell recently and haven't logged in for a few days.

"I don't believe i've seen that construct before."

I'm fairly certain I first saw that type of construct in the original Camel Book back in the '90s; I use it occasionally when it seems appropriate. There's currently similar code in "perlsyn: Basic BLOCKs".

The code in "perlsyn: Switch Statements" does much the same thing; however, I don't use the experimental given/when (switch) feature.

Anyway, thanks for looking and leaving a comment (++).

Another Way To Do It™ (tested and works):

my %DISPATCH_TABLE; BEGIN { %DISPATCH_TABLE = (
  n => sub { my ($oriented, $matrix) = @_;
    push $oriented->@*, $matrix->[$_] for reverse 0 .. $matrix->$#*;
  },
  s => sub { my ($oriented, $matrix) = @_;
    push $oriented->@*, $matrix->[$_] for 0 .. $matrix->$#*;
  },
  e => sub { my ($oriented, $matrix) = @_;
    for my $x (0 .. $matrix->$#*) {
      push $oriented->@*, my $col = [];
      for my $y (0 .. $matrix->[$x]->$#*) {
        push $col->@*, $matrix->[$y][$x];
      }
    }
  },
  w => sub { my ($oriented, $matrix) = @_;
    for my $x (0 .. $matrix->$#*) {
      push $oriented->@*, my $col = [];
      for my $y (reverse 0 .. $matrix->[$x]->$#*) {
        push $col->@*, $matrix->[$y][$x];
      }
    }
  },
); }
sub orient_matrix {
  my ($orient, $matrix) = @_;
  my $code = $DISPATCH_TABLE{$orient}
    or die "Unknown orientation '$orient'";
  $code->(my $oriented = [], $matrix);
  return $oriented;
}
[download]

Uhm, seems like i must have skipped (or since forgotten) a few chapters.

That's the really nice thing in Perl. "No matter what it is, you can use it in a boolean expression"

perl -e 'use Crypt::Digest::SHA256 qw[sha256_hex]; print substr(sha256_hex("the Answer To Life, The Universe And Everything"), 6, 2), "\n";'

Hmm... "&& do" https://perldoc.perl.org/perlfaq6#What-good-is-%5CG-in-a-regular-expression? https://perldoc.perl.org/5.6.2/perlsyn#Basic-BLOCKs-and-Switch-Statements