Variables & sigils

Declarators — my / our / constant

Full

How a name is introduced and scoped — lexical my, package our, immutable constant.

A declarator introduces a variable and fixes its scope. my is the everyday lexical declarator; our binds a name into the enclosing package; constant defines a compile-time immutable value.

my — lexical scope #

A my variable is visible from its declaration to the end of the enclosing block. An inner block can shadow an outer name.

my $x = 10;
{ my $x = 20; say $x; }
say $x;

Output

20
10

constant #

constant binds a name to a value once, at compile time; the value cannot be reassigned. The sigil is optional for scalars.

constant GREETING = "hi";
say GREETING;

Output

hi

our — package scope #

our declares a variable in the current package, reachable from outside by its fully-qualified Package::name.

our $g = 42;
say $g;
package Foo { our $bar = 99; }
say $Foo::bar;

Output

42
99

Notes #

Prefer my by default; reach for our only when a name must be visible across package boundaries.
A constant list is immutable. Raku++ gists a constant @array as [2 3 5 7], whereas Rakudo shows the immutable-List form (2 3 5 7) — a display difference only; the values are identical.
state is a fourth declarator — per-closure persistent storage — covered under State variables.