Closure Example

use strict;
use warnings;
use List::Util qw(sum);

# An example for closures in Perl,
# Also an example for two competing implementations of a function
# Here: the sum of all numbers of a column in an Array of Arrays

my @test = (
 [ "asd", "edsfsdfs", "345345545", "dasdas", "1,234.5" ],
 [ "asd", "edsfsdfs", "345345545", "dasdas", "1,234.5" ],
);

my $sum4 = colsum(4);
my $_sum4 = _colsum(4);

print $sum4->( \@test )."\n";
print $_sum4->( \@test )."\n";

sub colsum {
  my $idx = shift;
  return sub {
    my $result = 0;
    my @a = @{ scalar shift };
    foreach my $x (@a) {
      my $y = $x->[$idx];
      $y =~ s/,//g;
      $result += 1*$y;
    }
    return $result;
  }
}

sub _colsum {
  my $idx = shift;
  return sub {
    return sum map { $_->[$idx] =~ s/,//gr } @{ scalar shift };
  }
}