Why do you need $ when accessing array and hash elements in Perl?

Question

Since arrays and hashes can only contain scalars in Perl, why do you have to use the $ to tell the interpreter that the value is a scalar when accessing array or hash elements? In other words, assuming you have an array @myarray and a hash %myhash, why do you need to do:

$x = $myarray[1];
$y = $myhash{'foo'};

instead of just doing :

$x = myarray[1];
$y = myhash{'foo'};

Why are the above ambiguous?

Wouldn't it be illegal Perl code if it was anything but a $ in that place? For example, aren't all of the following illegal in Perl?

@var[0];
@var{'key'};
%var[0];
%var{'key'};

Answer 1

I've just used

my $x = myarray[1];

in a program and, to my surprise, here's what happened when I ran it:

$ perl foo.pl 
Flying Butt Monkeys!

That's because the whole program looks like this:

$ cat foo.pl 
#!/usr/bin/env perl

use strict;
use warnings;

sub myarray {
  print "Flying Butt Monkeys!\n";
}

my $x = myarray[1];

So myarray calls a subroutine passing it a reference to an anonymous array containing a single element, 1.

That's another reason you need the sigil on an array access.

Answer 2

Slices aren't illegal:

@slice = @myarray[1, 2, 5];
@slice = @myhash{qw/foo bar baz/};

And I suspect that's part of the reason why you need to specify if you want to get a single value out of the hash/array or not.