=> is exactly like the list seperator ,, but you can put barewords on the left hand side.

@a = ('a',   4);  # ok
@a = ('a' => 4);  # ok
@a = (a   => 4);  # ok
@a = (a,     4);  # XXX ERROR
print("Hello" => " " => "World" => "\n");  # Why not.

# Often used for hashes:
%h = ( key => 'value' );
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-> dereferences a reference:

@a = qw( a b c );
$ap = \@a;
print($ap->[2]);  # prints: c

%h = ( key => 'value' );
$hp = \%h;
print($hp->{key});  # prints: value

$obj = MyClass->new();
$obj->method();
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To interpolate something (as relevant here) is to substitute it with its value:

$a = 'test';
print('$a\n');   # prints: $a\n
print("$a\n");   # prints: test and a newline
print("\$a\n");  # prints: $a and a newline

@a = qw( a b c );
print('@a\n');   # prints: @a\n
print("@a\n");   # prints: abc and a newline
print("\@a\n");  # prints: @a and a newline
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