Scalars, arrays & hashes

The three sigils — $ for one item, @ for ordered lists, % for key/value maps.

A variable's sigil announces its shape. $ holds a single item (even if that item is itself a list), @ is a positional (ordered) container, and % is an associative (key/value) container.

Scalars — $ #

A $ variable holds exactly one thing. Assigning a list to it stores the list as one item, so .elems on the container is not what you might expect.

my $x = (1, 2, 3);
say $x.WHAT;
say $x.elems;

(List)
3

Arrays — @ #

An @ variable flattens an assigned list into an ordered container. say shows it in brackets; put prints the elements space-separated. Index with [ ] (zero-based).

my @a = 1, 2, 3;
say @a;
put @a;
say @a.elems;
say @a[1];

[1 2 3]
1 2 3
3
2

Hashes — % #

A % variable maps keys to values. Index with { }, or < > for constant string keys. Iteration order is not defined, so sort keys when you need determinism.

my %h = apple => 3, pear => 5;
say %h<apple>;
say %h.elems;
say %h.keys.sort;

3
2
(apple pear)

Notes #

• The sigil is part of the name: $x, @x, and %x are three different variables.
• @a[1] and %h<k> return the element; the sigil of the access follows the container, not the element.
• Because a $ scalar holds a list as a single item, passing $x where a list is wanted keeps it un-flattened — useful for nested data.