Documentation for routine Bool assembled from the following types:

class List

From List

(List) method Bool

Defined as:

method Bool(List:D: --> Bool:D)

Returns True if the list has at least one element, and False for the empty list.

say ().Bool;  # OUTPUT: «False␤» 
say (1).Bool; # OUTPUT: «True␤»

class Capture

From Capture

(Capture) method Bool

Defined as:

method Bool(Capture:D: --> Bool:D)

Returns True if the Capture contains at least one named or one positional argument.

say \(1,2,3, apples => 2).Bool;                   # OUTPUT: «True␤» 
say \().Bool;                                     # OUTPUT: «False␤»

class Promise

From Promise

(Promise) method Bool

multi method Bool(Promise:D:)

Returns True for a kept or broken promise, and False for one in state Planned.

role Baggy

From Baggy

(Baggy) method Bool

Defined as:

method Bool(Baggy:D: --> Bool:D)

Returns True if the invocant contains at least one element.

my $breakfast = ('eggs' => 1).BagHash;
say $breakfast.Bool;                              # OUTPUT: «True   (since we have one element)␤» 
$breakfast<eggs> = 0;                             # weight == 0 will lead to element removal 
say $breakfast.Bool;                              # OUTPUT: «False␤»

class Junction

From Junction

(Junction) method Bool

Defined as:

multi method Bool(Junction:D:)

Collapses the Junction and returns a single Boolean value according to the type and the values it holds. Every element is transformed to Bool.

my $n = Junction.new( "one", 1..6 );
say $n.Bool;                         # OUTPUT: «False␤» 

All elements in this case are converted to True, so it's false to assert that only one of them is.

my $n = Junction.new( "one", <0 1> );
say $n.Bool;                         # OUTPUT: «True␤» 

Just one of them is truish in this case, 1, so the coercion to Bool returns True.

role Setty

From Setty

(Setty) method Bool

Defined as:

multi method Bool(Setty:D: --> Bool:D)

Returns True if the invocant contains at least one element.

my $s1 = Set.new(1, 2, 3);
say $s1.Bool;                                     # OUTPUT: «True␤» 
 
my $s2 = $s1 ∩ Set.new(4, 5);                     # set intersection operator 
say $s2.Bool;                                     # OUTPUT: «False␤»

class Mu

From Mu

(Mu) routine Bool

multi sub    Bool(Mu --> Bool:D)
multi method Bool(   --> Bool:D)

Returns False on the type object, and True otherwise.

Many built-in types override this to be False for empty collections, the empty string or numerical zeros

say Mu.Bool;                    # OUTPUT: «False␤» 
say Mu.new.Bool;                # OUTPUT: «True␤» 
say [1, 2, 3].Bool;             # OUTPUT: «True␤» 
say [].Bool;                    # OUTPUT: «False␤» 
say %( hash => 'full' ).Bool;   # OUTPUT: «True␤» 
say {}.Bool;                    # OUTPUT: «False␤» 
say "".Bool;                    # OUTPUT: «False␤» 
say 0.Bool;                     # OUTPUT: «False␤» 
say 1.Bool;                     # OUTPUT: «True␤» 
say "0".Bool;                   # OUTPUT: «True␤»

class Str

From Str

(Str) method Bool

Defined as:

method Bool(Str:D: --> Bool:D)

Returns False if the string is empty, True otherwise.

class ComplexStr

From ComplexStr

(ComplexStr) method Bool

Defined as:

multi method Bool(ComplexStr:D: --> Bool:D)

This method may be provided by the parent classes and not implemented in ComplexStr directly.

Returns False if the invocant is numerically ±0±0i, otherwise returns True. String portion is not considered.

class Regex

From Regex

(Regex) method Bool

multi method Bool(Regex:D: --> Bool:D)

Matches against the caller's $_ variable, and returns True for a match or False for no match.

class Numeric

From Numeric

(Numeric) method Bool

multi method Bool(Numeric:D:)

Returns False if the number is equivalent to zero, and True otherwise.

class IntStr

From IntStr

(IntStr) method Bool

Defined as:

multi method Bool(IntStr:D: --> Bool:D)

This method may be provided by the parent classes and not implemented in IntStr directly.

Returns False if the invocant is numerically 0, otherwise returns True. String portion is not considered.

class NumStr

From NumStr

(NumStr) method Bool

Defined as:

multi method Bool(NumStr:D: --> Bool:D)

This method may be provided by the parent classes and not implemented in NumStr directly.

Returns False if the invocant is numerically ±0e0, otherwise returns True. String portion is not considered.

class StrDistance

From StrDistance

(StrDistance) method Bool

Returns True if before is different from after.

class RatStr

From RatStr

(RatStr) method Bool

Defined as:

multi method Bool(RatStr:D: --> Bool:D)

This method may be provided by the parent classes and not implemented in RatStr directly.

Returns False if the numerator of the numeric portion is 0, otherwise returns True. This applies for < 0/0 > zero-denominator RatStr as well, despite ?< 0/0 >.Num being True. String portion is not considered.

class Match

From Match

(Match) method Bool

Defined as:

method Bool(Capture:D: --> Bool:D)

Returns True on successful and False on unsuccessful matches. Please note that any zero-width match can also be successful.

say 'abc' ~~ /^/;                   # OUTPUT: «｢｣␤» 
say $/.from, ' ',  $/.to, ' ', ?$/; # OUTPUT: «0 0 True␤»

role Rational

From Rational

(Rational) method Bool

Defined as:

multi method Bool(Rational:D: --> Bool:D)

Returns False if numerator is 0, otherwise returns True. This applies for <0/0> zero-denominator Rational as well, despite ?<0/0>.Num being True.

role Blob

From Blob

(Blob) method Bool

Defined as:

multi method Bool(Blob:D:)

Returns False if and only if the buffer is empty.

my $blob = Blob.new();
say $blob.Bool; # OUTPUT: «False␤» 
$blob = Blob.new([1, 2, 3]);
say $blob.Bool; # OUTPUT: «True␤»

class Failure

From Failure

(Failure) method Bool

Defined as:

multi method Bool(Failure:D: --> Bool:D)

Returns False, and marks the failure as handled.

sub f() { fail }; my $v = f; say $v.handled; $v.Bool; say $v.handled;
# OUTPUT: «False␤ 
# True␤»

class Map

From Map

(Map) method Bool

Defined as:

method Bool(Map:D: --> Bool:D)

Returns True if the invocant contains at least one key/value pair.

my $m = Map.new('a' => 2, 'b' => 17);
say $m.Bool;                                      # OUTPUT: «True␤»