my @output = sort @input; # default sort using eq to compare values
my @output = sort {$a <=> $b} @input; # numeric sort
my @output = sort some_func @input; # custom algorithm

##</code><code>##

#!/usr/bin/perl -w

use strict;

my @input = (1..6);

my $calls;
my $fibcalls;

my @output = sort reorder @input; # how many calls to fib() ?

sub reorder {
  $calls++;
  return fib($a) <=> fib($b);
}

sub fib {
    my $val = shift;
    $fibcalls++;
    $val == 0 ? return $val:
      $val == 1 ? return $val :
	return fib($val - 1) + fib($val - 2);
}
print "called $calls times - fib calls $fibcalls\n";

##</code><code>##

cd /home/le6303/src/perl/
/usr/bin/perl -w "/home/le6303/src/perl/lister.pl" 
called 9 times - fib calls 150
##</code><code>##

#!/usr/bin/perl -w

use strict;

my @input = (1..6);

my @output = my_map(\&double, @input);

sub double {
    return 2 * shift;
}

sub my_map {
  my ($function, @values) = @_;

  my @results;
  foreach my $value (@values) {
     push @results, $function->($value);
  }

  return @results;
}

use Data::Dumper;
print Dumper \@output;;

##</code><code>##

cd /home/le6303/src/perl/
/usr/bin/perl -w "/home/le6303/src/perl/subber.pl" 
$VAR1 = [
          2,
          4,
          6,
          8,
          10,
          12
        ];

##</code><code>##

my @output = sort {$a <=> $b} map {fib($_)} @input;

##</code><code>##

#!/usr/bin/perl -w

use strict;

my @input = (1..6);

my $calls;
my $fib_calls;

my @output = sort {$calls++; $a <=> $b} map {fib($_)} @input;

sub fib {
    my $val = shift;
    $fib_calls++;
    $val == 0 ? return $val:
      $val == 1 ? return $val :
	return fib($val - 1) + fib($val - 2);
}

print "called $calls times - fib $fib_calls\n";
use Data::Dumper;
print Dumper(\@output);

##</code><code>##

cd /home/le6303/src/perl/
/usr/bin/perl -w "/home/le6303/src/perl/lister.pl" 
called 9 times - fib 58
$VAR1 = [
          1,
          1,
          2,
          3,
          5,
          8
        ];


##</code><code>##

my @output =  map {[$_, fib($_)]} @input;
##</code><code>##

cd /home/le6303/src/perl/
/usr/bin/perl -w "/home/le6303/src/perl/lister.pl" 
$VAR1 = [
          [
            1,
            1
          ],
          [
            2,
            1
          ],
          [
            3,
            2
          ],

          [
            4,
            3
          ],
          [
            5,
            5
          ],
          [
            6,
            8
          ]
        ];

##</code><code>##

my @output = map {$_->[0]}              # extract just the original
                                        # value from the tuple
             sort {$a->[1] <=> $b->[1]} # sort based on the
                                        # computed value
             map {[$_, some_func($_)]}  # create (value, computed)
                                        # tuples
             @input;