Operator classification

First, let's remind ourselves of some of the basic terminology that we need when talking about operators. Consider a simple example:

my $a = 10;
my $b = 20;
my $c = 0;
$c = $a + $b;
say $c; # 30

Let's concentrate on the following line of code:

$c = $a + $b;

Here, we tell the compiler to perform two actions—first, calculate the sum of the $a and $b variables, and second, assign the result to the third variable, that is, $c. There are two operators in this example—+ and =. Operators are presented by their one-character names. In this case, the names are chosen to copy the corresponding operators in mathematics. Later, we will see examples of other operators, which are not just a character. They can be, for example, a sequence of two or three non-alphabetical symbols, such as >= or <= operators. Or, they can be a string identifier...