Course of Raku / Essentials / More about types / Positional data types

Lists

Lists are similar to arrays but are immutable. It is not possible to change the size or the elements of a list. Use parentheses to create a list:

my $odd = (1, 3, 5, 7, 9);

Subscripting lists

To access individual elements of a list, use square brackets with the index:

say $odd[3]; # 7

Although, it is not possible to set a new value:

$odd[3] = 8; # Not OK

Such an attempt causes an exception:

Cannot modify an immutable List ((1 3 5 7 9))
  in block <unit> at t.raku line 4

Assigning a list to an array

What happens when you save a list in a variable with the @ sigil?

my @data = (40, 42, 44);

In this case, the @data variable contains an array, and you can modify its elements.

%%tipblock ## Variable vs list

Note that the fact that lists are immutable does not mean you cannot reuse the variable that keeps it.

my $elements = (1, 2);
say $elements[0]; # 1

$elements = (3, 4);
say $elements[0]; # 3