Perl 6 Essentials

Operators

Operators provide a simple syntax for manipulating values. Many of the Perl 6 operators will be familiar, especially to Perl programmers.

Assignment and Binding

The = operator is for ordinary assignment. It creates a copy of the values on the right-hand side and assigns them to the variables or data structures on the left-hand side:

$copy = $original;
@copies = @originals;

$copy and $original both have the same value, and @copies has a copy of every element in @originals.

The := operator is for binding assignment. Instead of copying the value from one variable or structure to the other, it creates an alias. An alias is an additional entry in the symbol table with a different name for the one container:

$a := $b;  # $a and $b are aliases
@c := @d;  # @c and @d are aliases

In this example, any change to $a also changes $b, because they’re just two separate names for the same container. Binding assignment requires the same number of elements on both sides, so both of these would be an error:

# ($a, $b) := ($c);          # error
# ($a, $b) := ($c, $d, $e);  # error

The ::= operator is a variant of the binding operator that binds at compile time.

Arithmetic Operators

The binary arithmetic operators are addition (+), subtraction (-), multiplication (*), division (/), modulus (%), and exponentiation (**). Each has a corresponding assignment operator (+=, -=, *=, /=, %=, **=) that combines the arithmetic operation with assignment:

$a = 3 + 5;
$a += 5;     # $a = $a + 5

The unary arithmetic ...