my @names = (
    'hoge',
    'fuga',
);

for my $result (@results) {
    print_sep();
}

while (my $record = <$results_file>) {
    chomp $record;
    my ($name, $votes) = split "\t", $record;
    print 'Vote for ',
    #略
}

while (my $record = <$results_file>) {
    chomp( $record );
    my ($name, $votes) = split("\t", $record);
    print(
        'Vote for ',
    #略
    );
}

$candidates[$i] = $incumbent{ $candidates[$i]{ get_region() } };

    if ($hoge) {
        $fuga++;
    }
    else {
        $hige++;
    }

$predicted_val
    = ($minimum + $maximum) / 2
      + $predicted_change * max($fudge_factor, $local_epsilon);

my @months = qw(
    January  February  March
    April    May       June
    July     August    September
    October  November  December
);

$escape_seq = "\177\006\030Z"; #これではなく

use charnames qw( :full );
$escape_seq = "\N{DELETE}\N{ACKNOWLEDGE}\N{CANCEL}Z"; #これを使う

$usage = "Usage: $0 <file> [-full]\n"
         . "(Use -full option for full dump)\n"
         ;

%default_service_record = {
    name => '<unkown>',
    rank => 'Recruit',
}

$text = format_text ({ src=>$raw_text, margins=>[1,62] });

Readonly my $ESCAPE_SEQ => "\N{DELETE}\N{ACKNOWLEDGE}\N{CANCEL}Z";

for ( @_ ? @_ : $_ ) {
    s{hoge}{}xms; # これは良くない
}

for my $orig_args ( @_ ? @_ : $_ ) {
    $orig_args =~ s{hoge}{}xms;# こうする
}

@frames[-1,-2,-3];
@active{'top', 'prev', 'backup'};

($frames[-1], $frames[-2], $frames[-3]);
($active{'top'}, $active{'prev'}, $active{'backup'});

for my $client (@clients) {
    $client->hoge(); # ok
}

for my $n (0..$#clients) {
    $clients[$n]->hoge(); # 重い
}

for my $trans_word (values %trans_for) {
    if ( $trans_word =~ m/hoge/xms) {
        $trans_word = 'FUGA'; # ok
    }
}

for my $orig_word (keys %trans_for) {
    if ( $trans_for{$orig_word} =~ m/hoge/xms) {
        $trans_for{$orig_word} = 'FUGA'; # 重い
    }
}

my @sqrt_results = map { sqrt $_ } @results;

@temperature = map { F_to_K($_) } @temperature; # 重い

for my $measurement (@temperature) {
    $measurement = F_to_K($measurement); # ok
}

my %sha512_of;

@sorted_scripts
    = sort { ($sha512_of{$a} ||= sha512($a))
                cmp
             ($sha512_of{$b} ||= sha512($b))
      }
      @scripts;

@sorted_scripts
    = map  { $_->[0] }
      sort { $a->[1] cmp $b->[1] }
      map  { [$_, sha512($_)] }
          @scripts;

    my @entries = map { $_->[1] }
        sort { $b->[0] <=> $a->[0] }
        map { [ $_->date, $_ ] } $self->entries;

    $self->{entries} = \@entries;

use Digest::SHA qw( sha512 );
use Memoize;
memoize('sha512');

@sorted_scripts = sort { sha512($a) cmp sha512($b) } @scripts;

add_email_addr(scalar reverse $email_address);

substr($addr, $country_pos, $COUNTRY_LEN)
    = $country_name($country_code); # 重い!

substr $addr, $country_pos, $COUNTRY_LEN, $country_name($country_code); # ok

my @files = glob($FILE_PATTERN);

• blessed $scalar
• refaddr $scalar
• reftype $scalar
• readonly $scalar
• tainted $scalar
• openhandle $scalar
• weaken $scalar
• is_weak $scalar
• looks_like_number $scalar

• first {<条件>} @list
• max @list
• maxstr @list
• min @list
• minstr @list
• shuffle @list
• sum @list
• reduce {<$a $bの2項演算>} @list

• all {<条件>} @list （any(), notall(), none()もある）
• first_index {<条件>} @list　（last_index()もある）
• apply {<変換>} @list　（リストのコピーに変換をかけて新しいリストを返す）
• pairwise {<$a $bの2項演算>} @array1, @array2
• zip @array1, @array2, ...
• uniq @list

sub hoge {
    my ($self, $context, $args) = @_;
    #略
}

sub say {
    return print @_, "\n";
}
#
say( 'Hello' );

my $cols = exists $args_ref->{cols} ? $args_ref->{cols} : $DEFAULT_WITDH;

open my $filehandle, '<', $filename

use IO::File;
my $active = IO::File->new($ACTIVE_LOG, '<')
    or croak "Can't open '$ACTILE_LOG': $OS_ERROR";

open my $stdin, '<', '-' or croak "Can't open stdin: $OS_ERROR";

open my $fh, '<', $config_file
    or croak "Can't open '$config_file': $OS_ERROR";

my @lines = <$fh>; # 読み込んだらすぐ閉じる
close $fh
    or croak "Can't close '$config_file' after reading: $OS_ERROR";

my $code = do { local $/; <$in> };

sysread $fh, $text, -s $fh;

use Perl6::Slurp;
my $text = slurp $file_handle;

my @lines = slurp $file_name;

my @lines = slurp $file_name, {chomp => 1};

print {$file} $name, $rank, $serial_num, "\n";

print {*STDERR} $name, $rank, $serial_num, "\n";

use IO::Handle
$file->print( $name, $rank, $serial_num, "\n" );
*STDERR->print( $name, $rank, $serial_num, "\n" );

print {*STDERR} 'Connecting to server...';

use IO::Handle;
*STDOUT->autoflush();

${$list_ref}[0] # NG

$list_ref->[0] # Ok

@{$list_ref}[0, -1]; # ok

$list_ref->[0, -1]; # same ($list_ref->[-1], undef);

use Scalar::Util qw( weaken );