class Set

class Set does Setty { }

An immutable set of unique values or objects. These values can be accessed via the { } postcircumfix, and always have a value of either True or False. For a mutable set, see SetHash.

sub set

sub set(*@args --> Set)

Creates a Set from the given @args

Type graph

Below you should see an image showing the type relations for Set. If not, try the PNG version.

perl6-type-graph Set Set Any Any Set->Any Setty Setty Set->Setty Mu Mu Any->Mu Associative Associative QuantHash QuantHash QuantHash->Associative Setty->QuantHash

Methods supplied by role Setty

Set does role Setty, which provides the following methods:

method grab

method grab($count = 1)

Like pick, a grab returns a random selection of elements, deleting the elements as they are picked. Unlike pick, it works only on mutable structures. Use of grab on an immutable structure results in an exception (much like push would).

method grabpairs

method grabpairs($count = 1)

Similar to grab, but instead of returning keys, returns the grabbed values as a list of Pair objects, whose keys are the deleted keys and whose values are True.

method pick

method pick($count = 1)

Returns $count elements chosen at random and without repetition from the Setty object.

method roll

method roll($count = 1)

method keys

The keys of a Setty object are just its elements. Therefore, keys simply returns a list of the object's elements.

method values

The values of a Setty object are always True. Therefore, values simply returns a list containing as many Trues as the object has elements

method kv

Returns a list of elements and True values interleaved.

method elems

method elems(--> Int)

The number of elements.

method total

method total(--> Int)

The total of all the values of the QuantHash object. For a Setty object, this is just the number of elements.

method new-fp

method new-fp(*@pairs --> Setty)

Creates a new Setty object from a list of pairs.

method ACCEPTS

method ACCEPTS($other)

Returns True if $other and self contain all the same elements, and no others.

Methods supplied by class Any

Set inherits from class Any, which provides the following methods:

method ACCEPTS

multi method ACCEPTS(Any:D: Mu $other)

Returns True if $other === self (i.e. it checks object identity).

method any

Interprets the invocant as a list and creates an any-Junction from it.

method all

Interprets the invocant as a list and creates an all-Junction from it.

method one

Interprets the invocant as a list and creates an one-Junction from it.

method none

Interprets the invocant as a list and creates an none-Junction from it.

Methods supplied by class Mu

Set inherits from class Mu, which provides the following methods:

method Str

multi method Str()   returns Str

Returns a string representation of the invocant, intended to be machine readable.

method clone

method clone(*%twiddles)

Creates a shallow clone of the invocant. If named arguments are passed to it, their values are used in every place where an attribute name matches the name of a named argument.

method new

multi method new(*%attrinit)

Default method for constructing (create + initialize) new objects of a class. This method expects only named arguments which are then used to initialize attributes with accessors of the same name.

Classes may provide their own new method to override this default.

method bless

method bless(*%attrinit) returns Mu:D

Lower-level object construction method than new.

Creates a new object of the same type as the invocant, uses the named arguments to initialize attributes, and returns the created object.

You can use this method when writing custom constructors:

class Point {
    has $.x;
    has $.y;
    multi method new($x, $y) {
        self.bless(:$x, :$y);
my $p =, 1);

(Though each time you write a custom constructor, remember that it makes subclassing harder).

method CREATE

method CREATE() returns Mu:D

Allocates a new object of the same type as the invocant, without initializing any attributes.

method print

multi method print() returns Bool:D

Prints value to $*OUT after stringification using .Str method without newline at end.

method say

multi method say() returns Bool:D

Prints value to $*OUT after stringification using .gist method with newline at end.

method ACCEPTS

multi method ACCEPTS(Mu:U: $other)

Performs a type check. Returns True if $other conforms to the invocant (which is always a type object or failure).

This is the method that is triggered on smart-matching against type objects, for example in if $var ~~ Int { ... }.

method WHICH

multi method WHICH() returns ObjAt:D

Returns an object of type ObjAt which uniquely identifies the object. Value types override this method which makes sure that two equivalent objects return the same return value from WHICH.