class FatRat

Rational number (arbitrary-precision)

class FatRat is Cool does Rational[Int, Int]

A FatRat is a rational number stored with arbitrary size numerator and denominator. Arithmetic operations involving a FatRat and optionally Int or Rat objects return a FatRat, avoiding loss of precision.

Since, unlike Rat, FatRat arithmetics do not fall back Num at some point, there is a risk that repeated arithmetic operations generate pathologically large numerators and denominators.

There are two common ways to generate FatRat objects: through the, Int) constructor, which generates them from numerator and denominator, or by calling the .FatRat method on an Int or Rat object.

Type graph

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

perl6-type-graph FatRat FatRat Cool Cool FatRat->Cool Rational Rational FatRat->Rational Mu Mu Any Any Any->Mu Cool->Any Numeric Numeric Real Real Real->Numeric Rational->Real

Methods supplied by role Rational

FatRat does role Rational, which provides the following methods:

method new

method new(NuT:D $numerator, DenomT:D $denominator) returns Rational:D

Creates a new rational object from numerator and denominator.

method numerator

method numerator(Rational:D:) returns NuT:D

Returns the numerator.

method denominator

method denominator(Rational:D:) returns DenomT:D

Returns the denominator.

method nude

method nude(Rational:D:) returns Positional

Returns a list of the numerator and denominator.

method norm

method norm(Rational:D:) returns Rational:D

Returns a normalized Rational object, i.e. with positive denominator, and numerator and denominator coprime.

Methods supplied by class Any

FatRat 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

FatRat 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.