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    <h2>Perl</h2> <ul> <li><p>Mixed use of sigils</p> <pre><code>my @array = ( 1, 2, 3 ); my $array = [ 4, 5, 6 ]; my $one = $array[0]; # not @array[0], you would get the length instead my $four = $array-&gt;[0]; # definitely not $array[0] my( $two, $three ) = @array[1,2]; my( $five, $six ) = @$array[1,2]; # coerce to array first my $length_a = @array; my $length_s = @$array; my $ref_a = \@array; my $ref_s = $array; </code></pre> <ul> <li><p>For example <strong>none</strong> of these are the same:</p> <pre><code>$array[0] # First element of @array @array[0] # Slice of only the First element of @array %array[0] # Syntax error $array-&gt;[0] # First element of an array referenced by $array @array-&gt;[0] # Deprecated first element of @array %array-&gt;[0] # Invalid reference $array{0} # Element of %array referenced by string '0' @array{0} # Slice of only one element of %array referenced by string '0' %array{0} # Syntax error $array-&gt;{0} # Element of a hash referenced by $array @array-&gt;{0} # Invalid reference %array-&gt;{0} # Deprecated Element of %array referenced by string '0' </code></pre></li> </ul> <p>In <code>Perl6</code> it is <a href="http://dev.perl.org/perl6/doc/design/syn/S09.html" rel="nofollow noreferrer">written</a>:</p> <pre><code>my @array = ( 1, 2, 3 ); my $array = [ 4, 5, 6 ]; my $one = @array[0]; my $four = $array[0]; # $array.[0] my( $two, $three ) = @array[1,2]; my( $five, $six ) = $array[1,2]; my $length_a = @array.length; my $length_s = $array.length; my $ref_a = @array; my $ref_s = $array; </code></pre></li> <li><p>Lack of true OO</p> <pre><code>package my_object; # fake constructor sub new{ bless {}, $_[0] } # fake properties/attributes sub var_a{ my $self = shift @_; $self-&gt;{'var_a'} = $_[0] if @_; $self-&gt;{'var_a'} } </code></pre> <p>In <code>Perl6</code> it is <a href="http://dev.perl.org/perl6/doc/design/syn/S12.html" rel="nofollow noreferrer">written</a>:</p> <pre><code>class Dog is Mammal { has $.name = "fido"; has $.tail is rw; has @.legs; has $!brain; method doit ($a, $b, $c) { ... } ... } </code></pre></li> <li><p>Poorly designed regex features</p> <pre><code>/(?=regexp)/; # look ahead /(?&lt;=fixed-regexp)/; # look behind /(?!regexp)/; # negative look ahead /(?&lt;!fixed-regexp)/; # negative look behind /(?&gt;regexp)/; # independent sub expression /(capture)/; # simple capture /(?:don't capture)/; # non-capturing group /(?&lt;name&gt;regexp)/; # named capture /[A-Z]/; # character class /[^A-Z]/; # inverted character class # '-' would have to be the first or last element in # the character class to include it in the match # without escaping it /(?(condition)yes-regexp)/; /(?(condition)yes-regexp|no-regexp)/; /\b\s*\b/; # almost matches Perl6's &lt;ws&gt; /(?{ print "hi\n" })/; # run perl code </code></pre> <p>In <code>Perl6</code> it is <a href="http://dev.perl.org/perl6/doc/design/syn/S05.html" rel="nofollow noreferrer">written</a>:</p> <pre><code>/ &lt;?before pattern&gt; /; # lookahead / &lt;?after pattern&gt; /; # lookbehind / regexp :: pattern /; # backtracking control / ( capture ) /; # simple capture / $&lt;name&gt;=[ regexp ] /; # named capture / [ don't capture ] /; # non-capturing group / &lt;[A..Z]&gt; /; # character class / &lt;-[A..Z]&gt; /; # inverted character class # you don't generally use '.' in a character class anyway / &lt;ws&gt; /; # Smart whitespace match / { say 'hi' } /; # run perl code </code></pre></li> <li><p>Lack of multiple dispatch</p> <pre><code>sub f( int $i ){ ... } # err sub f( float $i ){ ... } # err sub f($){ ... } # occasionally useful </code></pre> <p>In <code>Perl6</code> it is <a href="http://dev.perl.org/perl6/doc/design/syn/S06.html" rel="nofollow noreferrer">written</a>:</p> <pre><code>multi sub f( int $i ){ ... } multi sub f( num $i ){ ... } multi sub f( $i where $i == 0 ){ ... } multi sub f( $i ){ ... } # everything else </code></pre></li> <li><p>Poor Operator overloading</p> <pre><code>package my_object; use overload '+' =&gt; \&amp;add, ... ; </code></pre> <p>In <code>Perl6</code> it is <a href="http://dev.perl.org/perl6/doc/design/syn/S13.html" rel="nofollow noreferrer">written</a>:</p> <pre><code>multi sub infix:&lt;+&gt; (Us $us, Them $them) | (Them $them, Us $us) { ... } </code></pre></li> </ul>
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    1. POWhat are five things you hate about your favorite language?
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    1. USPhilip Potter
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    1. COI don't see lack of true OO as being as bad as you make it. Sometimes, it's a saviour, especially when the CPAN module you're using didn't think to expose what you need. And lack of multiple dispatch could be worse: perl could have been strongly typed ;-)
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    2. COBasically I went through the differences of Perl5 and Perl6.
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    3. COmy @two = @array[0,1];
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