is Mu While Mu is the root of the Raku class hierarchy, Any is the class that serves as a default base class for new classes, and as the base class for most built-in classes.
Since Raku intentionally confuses items and single-element lists, most methods in Any are also present on class List, and coerce to List or a list-like type.
Methods §
method ACCEPTS §
Defined as:
multi method ACCEPTS(Any: Mu )Usage:
EXPR.ACCEPTS(EXPR);
Returns True if $other === self (i.e. it checks object identity).
Many built-in types override this for more specific comparisons.
method any §
Defined as:
method any(--> Junction)Interprets the invocant as a list and creates an any-Junction from it.
say so 2 == <1 2 3>.any; # OUTPUT: «True» say so 5 == <1 2 3>.any; # OUTPUT: «False»method all §
Defined as:
method all(--> Junction)Interprets the invocant as a list and creates an all-Junction from it.
say so 1 < <2 3 4>.all; # OUTPUT: «True» say so 3 < <2 3 4>.all; # OUTPUT: «False»method one §
Defined as:
method one(--> Junction)Interprets the invocant as a list and creates a one-Junction from it.
say so 1 == (1, 2, 3).one; # OUTPUT: «True» say so 1 == (1, 2, 1).one; # OUTPUT: «False»method none §
Defined as:
method none(--> Junction)Interprets the invocant as a list and creates a none-Junction from it.
say so 1 == (1, 2, 3).none; # OUTPUT: «False» say so 4 == (1, 2, 3).none; # OUTPUT: «True»method list §
Defined as:
multi method list(Any:)multi method list(Any \SELF:)Applies the infix , operator to the invocant and returns the resulting List:
say 42.list.^name; # OUTPUT: «List» say 42.list.elems; # OUTPUT: «1»Subclasses of Any may choose to return any core type that does the Positional role from .list. Use .List to coerce specifically to List.
@ can also be used as a list or Positional contextualizer:
my = $[1,2,3];say .raku; # OUTPUT: «$[1, 2, 3]» my = @;say .^name; # OUTPUT: «Array» In the first case, the list is itemized. @ as a prefix puts the initial scalar in a list context by calling .list and turning it into an Array.
method push §
Defined as:
multi method push(Any \SELF: |values --> Positional)The method push is defined for undefined invocants and allows for autovivifying undefined to an empty Array, unless the undefined value implements Positional already. The argument provided will then be pushed into the newly created Array.
my ;say <a>; # OUTPUT: «(Any)» <-- Undefined <a>.push(1); # .push on Any say ; # OUTPUT: «{a => [1]}» <-- Note the Arrayroutine reverse §
Defined as:
multi sub reverse(* --> Seq)multi method reverse(List: --> Seq)Returns a Seq with the same elements in reverse order.
Note that reverse always refers to reversing elements of a list; to reverse the characters in a string, use flip.
Examples:
say <hello world!>.reverse; # OUTPUT: «(world! hello)» say reverse ^10; # OUTPUT: «(9 8 7 6 5 4 3 2 1 0)»method sort §
Defined as:
multi method sort()multi method sort()Sorts iterables with cmp or given code object and returns a new Seq. Optionally, takes a Callable as a positional parameter, specifying how to sort.
Examples:
say <b c a>.sort; # OUTPUT: «(a b c)» say 'bca'.comb.sort.join; # OUTPUT: «abc» say 'bca'.comb.sort().join; # OUTPUT: «cba» say '231'.comb.sort(:«<=>»).join; # OUTPUT: «123» sub by-character-count say <Let us impart what we have seen tonight unto young Hamlet>.sort();# OUTPUT: «(us we Let what have seen unto young impart Hamlet tonight)»routine map §
Defined as:
multi method map(\SELF: ;; :, :)multi sub map(, +values)multi method map(Hash \hash)multi method map(Iterable \iterable)multi method map(|c)map will iterate over the invocant and apply the number of positional parameters of the code object from the invocant per call. The returned values of the code object will become elements of the returned Seq.
The :$label and :$item are useful only internally, since for loops get converted to maps. The :$label takes an existing Label to label the .map's loop with and :$item controls whether the iteration will occur over (SELF,) (if :$item is set) or SELF.
In sub form, it will apply the code block to the values, which will be used as invocant.
The forms with |c, Iterable:D \iterable and Hash:D \hash as signatures will fail with X::Cannot::Map, and are mainly meant to catch common traps.
Inside a for statement that has been sunk, a Seq created by a map will also sink:
say gather for 1 # OUTPUT: «(0 1 2)» In this case, gather sinks the for statement, and the result of sinking the Seq will be iterating over its elements, calling .take on them.
method deepmap §
Defined as:
method deepmap( --> List) is nodaldeepmap will apply &block to each element and return a new List with the return values of &block, unless the element does the Iterable role. For those elements deepmap will descend recursively into the sublist.
say [[1,2,3],[[4,5],6,7]].deepmap(* + 1);# OUTPUT: «[[2 3 4] [[5 6] 7 8]]»In the case of Associatives, it will be applied to its values:
.deepmap( *.flip ).say# OUTPUT: «{a => (laer tsil), this => gniht, what => si}» method duckmap §
Defined as:
method duckmap() is rw is nodalduckmap will apply &block on each element that behaves in such a way that &block can be applied. If it fails, it will descend recursively if possible, or otherwise return the item without any transformation. It will act on values if the object is Associative.
<a b c d e f g>.duckmap(-> where <c d e>.any ).say;# OUTPUT: «(a b C D E f g)» (('d', 'e'), 'f').duckmap(-> where <e f>.any ).say;# OUTPUT: «((d E) F)» .duckmap(-> where <e f>.any ).say;# OUTPUT: «{first => (d E), second => F}» In the first case, it is applied to c, d and e which are the ones that meet the conditions for the block ({ .uc }) to be applied; the rest are returned as is.
In the second case, the first item is a list that does not meet the condition, so it's visited; that flat list will behave in the same way as the first one. In this case:
say [[1,2,3],[[4,5],6,7]].duckmap( *² ); # OUTPUT: «[9 9]»You can square anything as long as it behaves like a number. In this case, there are two arrays with 3 elements each; these arrays will be converted into the number 3 and squared. In the next case, however
say [[1,2,3],[[4,5],6.1,7.2]].duckmap( -> Rat );# OUTPUT: «[[1 2 3] [[4 5] 37.21 51.84]]»3-item lists are not Rat, so it descends recursively, but eventually only applies the operation to those that walk (or slither, as the case may be) like a Rat.
Although on the surface (and name), duckmap might look similar to deepmap, the latter is applied recursively regardless of the type of the item.
method nodemap §
Defined as:
method nodemap( --> List) is nodalnodemap will apply &block to each element and return a new List with the return values of &block. In contrast to deepmap it will not descend recursively into sublists if it finds elements which do the Iterable role.
say [[1,2,3], [[4,5],6,7], 7].nodemap(*+1);# OUTPUT: «(4, 4, 8)» say [[2, 3], [4, [5, 6]]]».nodemap(*+1)# OUTPUT: «((3 4) (5 3))»The examples above would have produced the exact same results if we had used map instead of nodemap. The difference between the two lies in the fact that map flattens out slips while nodemap doesn't.
say [[2,3], [[4,5],6,7], 7].nodemap();# OUTPUT: «(() () 7)» say [[2,3], [[4,5],6,7], 7].map();# OUTPUT: «(7)»When applied to Associatives, it will act on the values:
.nodemap( *.flip ).say;# OUTPUT: «{this => gniht, what => si}»method flat §
Defined as:
method flat() is nodalInterprets the invocant as a list, flattens non-containerized Iterables into a flat list, and returns that list. Keep in mind Map and Hash types are Iterable and so will be flattened into lists of pairs.
say ((1, 2), (3), %(:42a)); # OUTPUT: «((1 2) 3 {a => 42})» say ((1, 2), (3), %(:42a)).flat; # OUTPUT: «(1 2 3 a => 42)»Note that Arrays containerize their elements by default, and so flat will not flatten them. You can use the
hyper method call to call the .List method on all the inner Iterables and so de-containerize them, so that flat can flatten them:
say [[1, 2, 3], [(4, 5), 6, 7]] .flat; # OUTPUT: «([1 2 3] [(4 5) 6 7])» say [[1, 2, 3], [(4, 5), 6, 7]]».List.flat; # OUTPUT: «(1 2 3 4 5 6 7)»For more fine-tuned options, see deepmap, duckmap, and signature destructuring
method eager §
Defined as:
method eager() is nodalInterprets the invocant as a List, evaluates it eagerly, and returns that List.
my = 1..5;say ; # OUTPUT: «1..5» say .eager; # OUTPUT: «(1 2 3 4 5)»method elems §
Defined as:
multi method elems(Any: --> 1)multi method elems(Any:)Interprets the invocant as a list, and returns the number of elements in the list.
say 42.elems; # OUTPUT: «1» say <a b c>.elems; # OUTPUT: «3» say Whatever.elems ; # OUTPUT: «1»It will also return 1 for classes.
method end §
multi method end(Any: --> 0)multi method end(Any:)Interprets the invocant as a list, and returns the last index of that list.
say 6.end; # OUTPUT: «0» say <a b c>.end; # OUTPUT: «2»method pairup §
Defined as:
multi method pairup(Any:)multi method pairup(Any:)Returns an empty Seq if the invocant is a type object
Range.pairup.say; # OUTPUT: «()»Interprets the invocant as a list, and constructs a list of pairs from it, in the same way that assignment to a Hash does. That is, it takes two consecutive elements and constructs a pair from them, unless the item in the key position already is a pair (in which case the pair is passed through, and the next list item, if any, is considered to be a key again). It returns a Seq of Pairs.
say (a => 1, 'b', 'c').pairup.raku; # OUTPUT: «(:a(1), :b("c")).Seq»sub item §
Defined as:
multi item(\x)multi item(|c)multi item(Mu )Forces given object to be evaluated in item context and returns the value of it.
say item([1,2,3]).raku; # OUTPUT: «$[1, 2, 3]» say item( %( apple => 10 ) ).raku; # OUTPUT: «${:apple(10)}» say item("abc").raku; # OUTPUT: «"abc"»You can also use $ as item contextualizer.
say $[1,2,3].raku; # OUTPUT: «$[1, 2, 3]» say $("abc").raku; # OUTPUT: «"abc"»method Array §
Defined as:
method Array(--> Array) is nodalCoerces the invocant to an Array.
method List §
Defined as:
method List(--> List) is nodalCoerces the invocant to List, using the list method.
method serial §
Defined as
multi method serial()This method is Rakudo specific, and is not included in the Raku spec.
The method returns the self-reference to the instance itself:
my ; # defaults to Any say .serial.^name; # OUTPUT: «Any» say .^name; # OUTPUT: «Any» my = 'food';.serial.say; # OUTPUT: «food» This is apparently a no-op, as exemplified by the third example above. However, in HyperSeqs and RaceSeqs it returns a serialized Seq, so it can be considered the opposite of the hyper/race methods. As such, it ensures that we are in serial list-processing mode, as opposed to the autothreading mode of those methods.
method Hash §
Defined as:
multi method Hash( --> Hash)Coerces the invocant to Hash.
method hash §
Defined as:
multi method hash(Any:)multi method hash(Any:)When called on a type object, returns an empty Hash. On instances, it is equivalent to assigning the invocant to a %-sigiled variable and returning that.
Subclasses of Any may choose to return any core type that does the Associative role from .hash. Use .Hash to coerce specifically to Hash.
my ; # $d is Any say .hash; # OUTPUT: {} my is Map = a => 42, b => 666;say .hash; # Map.new((a => 42, b => 666)) say .Hash; # {a => 42, b => 666} method Slip §
Defined as:
method Slip(--> Slip) is nodalCoerces the invocant to Slip.
method Map §
Defined as:
method Map(--> Map) is nodalCoerces the invocant to Map.
method Seq §
Defined as:
method Seq() is nodalCoerces the invocant to Seq.
method Bag §
Defined as:
method Bag(--> Bag) is nodalCoerces the invocant to Bag, whereby Positionals are treated as lists of values.
method BagHash §
Defined as:
method BagHash(--> BagHash) is nodalCoerces the invocant to BagHash, whereby Positionals are treated as lists of values.
method Set §
Defined as:
method Set(--> Set) is nodalCoerces the invocant to Set, whereby Positionals are treated as lists of values.
method SetHash §
Defined as:
method SetHash(--> SetHash) is nodalCoerces the invocant to SetHash, whereby Positionals are treated as lists of values.
method Mix §
Defined as:
method Mix(--> Mix) is nodalCoerces the invocant to Mix, whereby Positionals are treated as lists of values.
method MixHash §
Defined as:
method MixHash(--> MixHash) is nodalCoerces the invocant to MixHash, whereby Positionals are treated as lists of values.
method Supply §
Defined as:
method Supply(--> Supply) is nodalFirst, it coerces the invocant to a list by applying its .list method, and then to a Supply.
routine min §
Defined as:
multi method min()multi method min()multi sub min(+args, :!)multi sub min(+args)Coerces the invocant to Iterable and returns the numerically smallest element; in the case of Hashes, it returns the Pair with the lowest value.
If a Callable positional argument is provided, each value is passed into the filter, and its return value is compared instead of the original value. The original value is still the one returned from min.
In sub form, the invocant is passed as an argument and a comparison Callable can be specified with the named argument :by.
say (1,7,3).min(); # OUTPUT:«1» say (1,7,3).min(); # OUTPUT:«7» say min(1,7,3); # OUTPUT: «1» say min(1,7,3,:by( )); # OUTPUT: «7» min( %(a => 3, b=> 7 ) ).say ; # OUTPUT: «a => 3»routine max §
Defined as:
multi method max()multi method max()multi sub max(+args, :!)multi sub max(+args)Coerces the invocant to Iterable and returns the numerically largest element; in the case of Hashes, the Pair with the highest value.
If a Callable positional argument is provided, each value is passed into the filter, and the return value is compared instead of the original value. The original value is still the one returned from max.
In sub form, the invocant is passed as an argument and a comparison Callable can be specified with the named argument :by.
say (1,7,3).max(); # OUTPUT:«7» say (1,7,3).max(); # OUTPUT:«1» say max(1,7,3,:by( )); # OUTPUT: «1» say max(1,7,3); # OUTPUT: «7» max( %(a => 'B', b=> 'C' ) ).say; # OUTPUT: «b => C»routine minmax §
Defined as:
multi method minmax()multi method minmax()multi sub minmax(+args, :!)multi sub minmax(+args)Returns a Range from the smallest to the largest element.
If a Callable positional argument is provided, each value is passed into the filter, and its return value is compared instead of the original value. The original values are still used in the returned Range.
In sub form, the invocant is passed as an argument and a comparison Callable can be specified with the named argument :by.
say (1,7,3).minmax(); # OUTPUT:«1..7» say (1,7,3).minmax(); # OUTPUT:«7..1» say minmax(1,7,3); # OUTPUT: «1..7» say minmax(1,7,3,:by( -* )); # OUTPUT: «7..1»method minpairs §
Defined as:
multi method minpairs(Any:)Calls .pairs and returns a Seq with all of the Pairs with minimum values, as judged by the cmp operator:
<a b c a b c>.minpairs.raku.put; # OUTPUT: «(0 => "a", 3 => "a").Seq» %(:42a, :75b).minpairs.raku.put; # OUTPUT: «(:a(42),).Seq»method maxpairs §
Defined as:
multi method maxpairs(Any:)Calls .pairs and returns a Seq with all of the Pairs with maximum values, as judged by the cmp operator:
<a b c a b c>.maxpairs.raku.put; # OUTPUT: «(2 => "c", 5 => "c").Seq» %(:42a, :75b).maxpairs.raku.put; # OUTPUT: «(:b(75),).Seq»method keys §
Defined as:
multi method keys(Any: --> List)multi method keys(Any: --> List)For defined Any returns its keys after calling list on it, otherwise calls list and returns it.
my = Set(<Þor Oðin Freija>);say .keys; # OUTPUT: «(Þor Oðin Freija)»See also List.keys.
Trying the same on a class will return an empty list, since most of them don't really have keys.
method flatmap §
Defined as:
method flatmap(, :)DEPRECATION NOTICE: This method is deprecated in 6.d and will be removed in 6.e. Use .map followed by .flat instead.
Applies map to every element with the block and Label used as an argument and flattens out the result using .flat.
say "aabbccc".comb.Mix.flatmap: "→ " ~ *; # OUTPUT: «(→ b␉2 → c␉3 → a␉2)»In this case, the elements of the Mix are itemized to key␉value, and then mapped and flattened. Same result as
say "aabbccc".comb.Mix.map( "→ " ~ * ).flatWhich is why it is deprecated in 6.d and will be eventually eliminated in 6.e.
method roll §
Defined as:
multi method roll(--> Any)multi method roll( --> Seq)Coerces the invocant to a list by applying its .list method and uses List.roll on it.
my Mix = ("þ" xx 3, "ð" xx 4, "ß" xx 5).Mix;say .roll; # OUTPUT: «ð» say .roll(5); # OUTPUT: «(ß ß þ ß þ)»$m, in this case, is converted into a list and then a (weighted in this case) dice is rolled on it. See also List.roll for more information.
method iterator §
Defined as:
multi method iterator(Any:)Returns the object as an iterator after converting it to a list. This is the function called from the for statement.
.say for 3; # OUTPUT: «3»Most subclasses redefine this method for optimization, so it's mostly types that do not actually iterate the ones that actually use this implementation.
method pick §
Defined as:
multi method pick(--> Any)multi method pick( --> Seq)Coerces the invocant to a list by applying its .list method and uses List.pick on it.
my Range = 'α'..'ω';say .pick(3); # OUTPUT: «(β α σ)»method skip §
Defined as:
multi method skip()multi method skip(Whatever)multi method skip(Callable )multi method skip(Int() )Creates a Seq from 1-item list's iterator and uses Seq.skip on it, please check that document for real use cases; calling skip without argument is equivalent to skip(1).
Calling it with Whatever will return an empty iterator:
say <1 2 3>.skip(*); # OUTPUT: «()»The multi that uses a Callable is intended mainly to be used this way:
say <1 2 3>.skip(*-1); # OUTPUT: «(3)»Instead of throwing away the first $n elements, it throws away everything but the elements indicated by the WhateverCode, in this case all but the last one.
method are §
Defined as:
multi method are()Returns the strictest type (or role) to which all elements of the list will smartmatch. Returns Nil on an empty list.
say (1,2,3).are; # OUTPUT: «(Int)» say <a b c>.are; # OUTPUT: «(Str)» say <42 666>.are; # OUTPUT: «(IntStr)» say (42,666e0).are; # OUTPUT: «(Real)» say (42,i).are; # OUTPUT: «(Numeric)» say ("a",42,3.14).are; # OUTPUT: «(Cool)»Available as of release 2022.02 of the Rakudo compiler.
method prepend §
Defined as:
multi method prepend(Any: --> Array)multi method prepend(Any: --> Array)Called with no arguments on an empty variable, it initializes it as an empty Array; if called with arguments, it creates an array and then applies Array.prepend on it.
my ;say .prepend; # OUTPUT: «[]» say ; # OUTPUT: «[]» my ;say .prepend(1,2,3); # OUTPUT: «[1 2 3]»method unshift §
Defined as:
multi method unshift(Any: --> Array)multi method unshift(Any: --> Array)Initializes Any variable as empty Array and calls Array.unshift on it.
my ;say .unshift; # OUTPUT: «[]» say ; # OUTPUT: «[]» my ;say .unshift([1,2,3]); # OUTPUT: «[[1 2 3]]»routine first §
Defined as:
multi method first(Bool )multi method first(Regex , :, *)multi method first(Callable , :, * is copy)multi method first(Mu , :, *)multi method first(:, *)multi sub first(Bool , |)multi sub first(Mu , +values, *)In general, coerces the invocant to a list by applying its .list method and uses List.first on it.
However, this is a multi with different signatures, which are implemented with (slightly) different behavior, although using it as a subroutine is equivalent to using it as a method with the second argument as the object.
For starters, using a Bool as the argument will always return a Failure. The form that uses a $test will return the first element that smartmatches it, starting from the end if :end is used.
say (3..33).first; # OUTPUT: «3» say (3..33).first(:end); # OUTPUT: «33» say (⅓,⅔…30).first( 0xF ); # OUTPUT: «15» say first 0xF, (⅓,⅔…30); # OUTPUT: «15» say (3..33).first( /\d\d/ ); # OUTPUT: «10»The third and fourth examples use the Mu $test forms which smartmatches and returns the first element that does. The last example uses as a test a regex for numbers with two figures, and thus the first that meets that criterion is number 10. This last form uses the Callable multi:
say (⅓,⅔…30).first( * %% 11, :end, :kv ); # OUTPUT: «(65 22)»Besides, the search for first will start from the :end and returns the set of key/values in a list; the key in this case is simply the position it occupies in the Seq. The :kv argument, which is part of the %a argument in the definitions above, modifies what first returns, providing it as a flattened list of keys and values; for a listy object, the key will always be the index.
From version 6.d, the test can also be a Junction:
say (⅓,⅔…30).first( 3 | 33, :kv ); # OUTPUT: «(8 3)»method unique §
Defined as:
multi method unique()multi method unique( :!, :! )multi method unique( :! )multi method unique( :! )Creates a sequence of unique elements either of the object or of values in the case it's called as a sub.
<1 2 2 3 3 3>.unique.say; # OUTPUT: «(1 2 3)» say unique <1 2 2 3 3 3>; # OUTPUT: «(1 2 3)»The :as and :with parameters receive functions that are used for transforming the item before checking equality, and for checking equality, since by default the === operator is used:
("1", 1, "1 ", 2).unique( as => Int, with => &[==] ).say; # OUTPUT: «(1 2)»Please see unique for additional examples that use its sub form.
method repeated §
Defined as:
multi method repeated()multi method repeated( :!, :! )multi method repeated( :! )multi method repeated( :! )Similarly to unique, finds repeated elements in values (as a routine) or in the object, using the :as associative argument as a normalizing function and :with as equality function.
<1 -1 2 -2 3>.repeated(:as(),:with(&[==])).say; # OUTPUT: «(-1 -2)» (3+3i, 3+2i, 2+1i).repeated(as => *.re).say; # OUTPUT: «(3+2i)»It returns the last repeated element before normalization, as shown in the example above. See repeated for more examples that use its sub form.
method squish §
Defined as:
multi method squish( :!, : = &[===] )multi method squish( : = &[===] )Similar to .repeated, returns the sequence of first elements of contiguous sequences of equal elements, after normalization by the function :as, if present, and using as an equality operator the :with argument or === by default.
"aabbccddaa".comb.squish.say; # OUTPUT: «(a b c d a)» "aABbccdDaa".comb.squish( :as() ).say; # OUTPUT: «(a B c d a)» (3+2i,3+3i,4+0i).squish( as => *.re, with => &[==]).put; # OUTPUT: «3+2i 4+0i» As shown in the last example, a sequence can contain a single element. See squish for additional sub examples.
method permutations §
Defined as:
method permutations(|c)Coerces the invocant to a list by applying its .list method and uses List.permutations on it.
say <a b c>.permutations;# OUTPUT: «((a b c) (a c b) (b a c) (b c a) (c a b) (c b a))» say set(1,2).permutations;# OUTPUT: «((2 => True 1 => True) (1 => True 2 => True))»Permutations of data structures with a single or no element will return a list containing an empty list or a list with a single element.
say 1.permutations; # OUTPUT: «((1))»method join §
Defined as
method join( = '') is nodalConverts the object to a list by calling self.list, and calls .join on the list. Can take a separator, which is an empty string by default.
(1..3).join.say; # OUTPUT: «123» <a b c>.join("❧").put; # OUTPUT: «a❧b❧c»routine categorize §
Defined as:
multi method categorize()multi method categorize(Whatever)multi method categorize(, :!, :)multi method categorize(, :)multi sub categorize(, +items, :!, * )multi sub categorize(, +items, * )The two first forms fail with an error message.
In its simplest form, it uses a $test whose result will be used as a key; the values of the key will be an array of the elements that produced that key as a result of the test.
say (1..13).categorize( * %% 3);say categorize( * %% 3, 1..13)# OUTPUT: «{False => [1 2 4 5 7 8 10 11 13], True => [3 6 9 12]}» The :as argument will normalize before categorizing
say categorize( * %% 3, -5..5, as => )# OUTPUT: «{False => [5 4 2 1 1 2 4 5], True => [3 0 3]}» The $into associative argument can be used to put the result instead of returning a new Hash
my ;my = (2002..2009).map( );.categorize( *.is-leap-year , into => );say # OUTPUT: # «{ False # => [2002-01-01 2003-01-01 2005-01-01 2006-01-01 2007-01-01 2009-01-01], # True => [2004-01-01 2008-01-01]}» The function used to categorize can return an array indicating all possible bins their argument can be put into:
sub divisible-by( Int --> Array(Seq) ) say (3..13).categorize( );# OUTPUT: # «{2 => [4 6 8 10 12], 3 => [3 6 9 12], 5 => [5 10], 7 => [7]}» In this case, every number in the range is classified in as many bins as it can be divided by.
routine classify §
Defined as:
multi method classify()multi method classify(Whatever)multi method classify(, :!, :)multi method classify(, :)multi sub classify(, +items, :!, * )multi sub classify(, +items, * )The two first forms will fail. The rest include a $test, which is a function that will return a scalar for every input; these will be used as keys of a hash whose values will be arrays with the elements that output that key for the test function.
my = (2003..2008).map( );.classify( *.is-leap-year , into => my );say ;# OUTPUT: «{False => [2003-01-01 2005-01-01 2006-01-01 2007-01-01], # True => [2004-01-01 2008-01-01]}» Similarly to .categorize, elements can be normalized by the Callable passed with the :as argument, and it can use the :into named argument to pass a Hash the results will be classified into; in the example above, it's defined on the fly.
From version 6.d, .classify will also work with Junctions.
routine reduce §
Defined as:
multi method reduce(Any: & --> Nil)multi method reduce(Any: )multi sub reduce (, +list)This routine combines the elements in a list-y object, and produces a single result, by applying a binary subroutine. It applies its argument (or first argument for the sub form) as an operator to all the elements in the object (or second argument for the sub form), producing a single result. The subroutine must be either an infix operator or take two positional arguments. When using an infix operator, we must provide the code object of its subroutine version, i.e., the operator category, followed by a colon, then a list quote construct with the symbol(s) that make up the operator (e.g., infix:<+>). See Operators.
say (1..4).reduce(:<+>); # OUTPUT: «10» say reduce :<+>, 1..4; # OUTPUT: «10» say reduce , 1..4; # OUTPUT: «1» sub hyphenate(Str \a, Str \b) say reduce , 'a'..'c'; # OUTPUT: «a-b-c»Applied to a class, the routine will always return Nil.
say Range.reduce(:<+>); # OUTPUT: «Nil» say Str.reduce(:<~>); # OUTPUT: «Nil»See List.reduce for a more thorough discussion.
routine produce §
Defined as:
multi method produce(Any: & --> Nil)multi method produce(Any: )multi sub produce (, +list)This is similar to reduce, but returns a list with the accumulated values instead of a single result.
<10 5 3>.reduce( &[*] ).say ; # OUTPUT: «150» <10 5 3>.produce( &[*] ).say; # OUTPUT: «(10 50 150)» The last element of the produced list would be the output produced by the .reduce method.
If it's a class, it will simply return Nil.
method pairs §
Defined as:
multi method pairs(Any:)multi method pairs(Any:)Returns an empty List if the invocant is a type object:
say Num.pairs; # OUTPUT: «()»For a value object, it converts the invocant to a List via the list method and returns the result of List.pairs on it.
<1 2 2 3 3 3>.Bag.pairs.say;# OUTPUT: «(1 => 1 3 => 3 2 => 2)»In this case, every element (with weight) in a bag is converted to a pair.
method antipairs §
Defined as:
multi method antipairs(Any:)multi method antipairs(Any:)Returns an empty List if the invocant is a type object
Range.antipairs.say; # OUTPUT: «()»If it's a value object, it returns the inverted list of pairs after converting it to a list of pairs; the values will become keys and the other way round.
%(s => 1, t=> 2, u => 3).antipairs.say ;# OUTPUT: «(2 => t 1 => s 3 => u)»method invert §
Defined as:
multi method invert(Any:)multi method invert(Any:)Applied to a type object will return an empty list; applied to an object will convert it to a list and apply List.invert to it, that is, interchange key with value in every Pair. The resulting list needs to be a list of Pairs.
"aaabbcccc".comb.Bag.invert.say; # OUTPUT: «(4 => c 3 => a 2 => b)»In this case, a Bag can be converted to a list of Pairs. If the result of converting the object to a list is not a list of pairs, the method will fail.
routine kv §
Defined as:
multi method kv(Any:)multi method kv(Any:)multi sub kv()Returns an empty List if the invocant is a type object:
Sub.kv.say ;# OUTPUT: «()»It calls list on the invocant for value objects and returns the result of List.kv on it as a list where keys and values will be ordered and contiguous
<1 2 3>.kv.say; # OUTPUT: «(0 1 1 2 2 3)»In the case of Positionals, the indices will be considered keys.
method toggle §
Defined as:
method toggle(Any: * where .all ~~ Callable, Bool : --> Seq)Iterates over the invocant, producing a Seq, toggling whether the received values are propagated to the result on and off, depending on the results of calling Callables in @conditions:
say (1..15).toggle(* < 5, * > 10, * < 15); # OUTPUT: «(1 2 3 4 11 12 13 14)» say (1..15).toggle(:off, * > 2, * < 5, * > 10, * < 15); # OUTPUT: «(3 4 11 12 13 14)» Imagine a switch that's either on or off (True or False), and values are produced if it's on. By default, the initial state of that switch is in "on" position, unless :$off is set to a true value, in which case the initial state will be "off".
A Callable from the head of @conditions is taken (if any are available) and it becomes the current tester. Each value from the original sequence is tested by calling the tester Callable with that value. The state of our imaginary switch is set to the return value from the tester: if it's truthy, set switch to "on", otherwise set it to "off".
Whenever the switch is toggled (i.e. switched from "off" to "on" or from "on" to "off"), the current tester Callable is replaced by the next Callable in @conditions, if available, which will be used to test any further values. If no more tester Callables are available, the switch will remain in its current state until the end of iteration.
# our original sequence of elements: say list ^10; # OUTPUT: «(0 1 2 3 4 5 6 7 8 9)» # toggled result: say ^10 .toggle: * < 4, * %% 2, ; # OUTPUT: «(0 1 2 3 6 7)» # First tester Callable is `* < 4` and initial state of switch is "on". # As we iterate over our original sequence: # 0 => 0 < 4 === True switch is on, value gets into result, switch is # toggled, so we keep using the same Callable: # 1 => 1 < 4 === True same # 2 => 2 < 4 === True same # 3 => 3 < 4 === True same # 4 => 4 < 4 === False switch is now off, "4" does not make it into the # result. In addition, our switch got toggled, so # we're switching to the next tester Callable # 5 => 5 %% 2 === False switch is still off, keep trying to find a value # 6 => 6 %% 2 === True switch is now on, take "6" into result. The switch # toggled, so we'll use the next tester Callable # 7 => is-prime(7) === True switch is still on, take value and keep going # 8 => is-prime(8) === False switch is now off, "8" does not make it into # the result. The switch got toggled, but we # don't have any more tester Callables, so it # will remain off for the rest of the sequence. Since the toggle of the switch's state loads the next tester Callable, setting :$off to a True value affects when first tester is discarded:
# our original sequence of elements: say <0 1 2>; # OUTPUT: «(0 1 2)» # toggled result: say <0 1 2>.toggle: * > 1; # OUTPUT: «()» # First tester Callable is `* > 1` and initial state of switch is "on". # As we iterate over our original sequence: # 0 => 0 > 1 === False switch is off, "0" does not make it into result. # In addition, switch got toggled, so we change the # tester Callable, and since we don't have any more # of them, the switch will remain "off" until the end The behavior changes when :off is used:
# our original sequence of elements: say <0 1 2>; # OUTPUT: «(0 1 2)» # toggled result: say <0 1 2>.toggle: :off, * > 1; # OUTPUT: «(2)» # First tester Callable is `* > 1` and initial state of switch is "off". # As we iterate over our original sequence: # 0 => 0 > 1 === False switch is off, "0" does not make it into result. # The switch did NOT get toggled this time, so we # keep using our current tester Callable # 1 => 1 > 1 === False same # 2 => 2 > 1 === True switch is on, "2" makes it into the result method head §
Defined as:
multi method head(Any:) is rawmulti method head(Any: Callable )multi method head(Any: )Returns either the first element in the object, or the first $n if that's used.
"aaabbc".comb.Mix.head.put; # OUTPUT: «c␉1» "aaabbc".comb.Mix.head.put; # OUTPUT: «a␉3» say ^10 .head(5); # OUTPUT: «(0 1 2 3 4)» say ^∞ .head(5); # OUTPUT: «(0 1 2 3 4)» say ^10 .head; # OUTPUT: «0» say ^∞ .head; # OUTPUT: «0»In the first two cases, the results are different since there's no defined order in Mixes. In the other cases, it returns a Seq. A Callable can be used to return all but the last elements:
say (^10).head( * - 3 );# OUTPUT: «(0 1 2 3 4 5 6)»method tail §
Defined as:
multi method tail() is rawmulti method tail()Returns the last or the list of the $n last elements of an object. $n can be a Callable, usually a WhateverCode, which will be used to get all but the first n elements of the object.
say (^12).reverse.tail ; # OUTPUT: «0» say (^12).reverse.tail(3); # OUTPUT: «(2 1 0)» say (^12).reverse.tail(*-7); # OUTPUT: «(4 3 2 1 0)» method tree §
Defined as:
multi method tree(Any:)multi method tree(Any:)multi method tree(Any: Whatever )multi method tree(Any: Int(Cool) )multi method tree(Any: @ [, *])multi method tree(Any: , *)Returns the class if it's undefined or if it's not Iterable, returns the result of applying the tree method to its invocant otherwise.
say Any.tree; # OUTPUT: «Any».tree has different prototypes for Iterable elements.
my = ( 'A', ('B','C', ('E','F','G')));say .tree(1).flat.elems; # OUTPUT: «6» say .tree(2).flat.elems; # OUTPUT: «2» say .tree( *.join("-"),*.join("—"),*.join("|"));# OUTPUT: «A-B—C—E|F|G» With a number, it iteratively applies tree to every element in the lower level; the first instance will apply .tree(0) to every element in the array, and likewise for the next example.
The second prototype applies the Whatever code passed as arguments to every level in turn; the first argument will go to level 1 and so on. tree can, thus, be a great way to process complex all levels of complex, multi-level, data structures.
method nl-out §
Defined as:
method nl-out(--> Str)Returns Str with the value of "\n". See IO::Handle.nl-out for the details.
Num.nl-out.print; # OUTPUT: «» Whatever.nl-out.print;# OUTPUT: «» 33.nl-out.print; # OUTPUT: «»method combinations §
Defined as:
method combinations(|c)Coerces the invocant to a list by applying its .list method and uses List.combinations on it.
say (^3).combinations; # OUTPUT: «(() (0) (1) (2) (0 1) (0 2) (1 2) (0 1 2))» Combinations on an empty data structure will return a list with a single element, an empty list; on a data structure with a single element it will return a list with two lists, one of them empty and the other with a single element.
say set().combinations; # OUTPUT: «(())»method grep §
Defined as:
method grep(Mu , :, :, :, : --> Seq)Coerces the invocant to a list by applying its .list method and uses List.grep on it.
For undefined invocants, based on $matcher the return value can be either ((Any)) or the empty List.
my ;say .grep(); # OUTPUT: «((Any))» say .grep(); # OUTPUT: «()»method append §
Defined as:
multi method append(Any \SELF: |values)In the case the instance is not a positional-thing, it instantiates it as a new Array, otherwise clone the current instance. After that, it appends the values passed as arguments to the array obtained calling Array.append on it.
my ;say .append; # OUTPUT: «[]» my ;say .append((1,2,3)); # OUTPUT: «[1 2 3]»method values §
Defined as:
multi method values(Any:)multi method values(Any:)Will return an empty list for undefined or class arguments, and the object converted to a list otherwise.
say (1..3).values; # OUTPUT: «(1 2 3)» say List.values; # OUTPUT: «()»method collate §
Defined as:
method collate()The collate method sorts taking into account Unicode grapheme characteristics; that is, sorting more or less as one would expect instead of using the order in which their codepoints appear. collate will behave this way if the object it is applied to is Iterable.
say ('a', 'Z').sort; # (Z a) say ('a', 'Z').collate; # (a Z) say <ä a o ö>.collate; # (a ä o ö) my = 'aa' => 'value', 'Za' => 'second';say .collate; # (aa => value Za => second); This method is affected by the $*COLLATION variable, which configures the four collation levels. While Primary, Secondary and Tertiary mean different things for different scripts, for the Latin script used in English they mostly correspond with Primary being Alphabetic, Secondary being Diacritics and Tertiary being Case.
In the example below you can see how when we disable tertiary collation which in Latin script generally is for case, and also disable quaternary which breaks any ties by checking the codepoint values of the strings, we get Same back for A and a:
.set(:quaternary(False), :tertiary(False));say 'a' coll 'A'; # OUTPUT: «Same» say ('a','A').collate == ('A','a').collate; # OUTPUT: «True»The variable affects the coll operator as shown as well as this method.
method cache §
Defined as:
method cache()Provides a List representation of the object itself, calling the method list on the instance.
method batch §
Defined as:
multi method batch(Int )multi method batch(Int :!)Coerces the invocant to a list by applying its .list method and uses List.batch on it.
method rotor §
Defined as:
multi method rotor(Any: Int , :)multi method rotor(Any: *, :)Creates a Seq that groups the elements of the object in lists of $batch elements.
say (3..9).rotor(3); # OUTPUT: «((3 4 5) (6 7 8))»With the :partial named argument, it will also include lists that do not get to be the $batch size:
say (3..10).rotor(3, :partial); # OUTPUT: «((3 4 5) (6 7 8) (9 10))».rotor can be called with an array of integers and pairs, which will be applied in turn. While integers will establish the batch size, as above, Pairs will use the key as batch size and the value as number of elements to skip if it's positive, or overlap if it's negative.
say (3..11).rotor(3, 2 => 1, 3 => -2, :partial);# OUTPUT: «((3 4 5) (6 7) (9 10 11) (10 11))»In this case, the first batch (ruled by an integer) has 3 elements; the second one has 2 elements (key of the pair), but skips one (the number 8); the third one has size 2 (because partials are allowed), and an overlap of 2 also.
The overlap cannot be larger than the sublist size; in that case, it will throw an Exception:
say (3..11).rotor(3, 2 => 1, 3 => -4, :partial);# OUTPUT: «(exit code 1) Rotorizing gap is out of range. Is: -4, should be in # -3..^Inf; Ensure a negative gap is not larger than the length of the # sublist » Non-Int values of $batch will be coerced to Int:
say (3..9).rotor(3+⅓); # OUTPUT: «((3 4 5) (6 7 8))»Please see also list.rotor for examples applied to lists.
method sum §
Defined as:
method sum() is nodalIf the content is iterable, it returns the sum of the values after pulling them one by one, or 0 if the list is empty.
(3,2,1).sum; # OUTPUT: «6» say 3.sum; # OUTPUT: «3» It will fail if any of the elements cannot be converted to a number.
Type Graph §
Any
Routines supplied by class Mu §
Any inherits from class Mu, which provides the following routines:
(Mu) method iterator §
Defined as:
method iterator(--> Iterator)Coerces the invocant to a list by applying its .list method and uses iterator on it.
my = Mu.iterator;say .pull-one; # OUTPUT: «(Mu)» say .pull-one; # OUTPUT: «IterationEnd»(Mu) method defined §
Declared as
multi method defined( --> Bool)Returns False on a type object, and True otherwise.
say Int.defined; # OUTPUT: «False» say 42.defined; # OUTPUT: «True»A few types (like Failure) override defined to return False even for instances:
sub fails() ;say fails().defined; # OUTPUT: «False»(Mu) routine defined §
Declared as
multi sub defined(Mu --> Bool)invokes the .defined method on the object and returns its result.
(Mu) routine isa §
multi method isa(Mu --> Bool)multi method isa(Str --> Bool)Returns True if the invocant is an instance of class $type, a subset type or a derived class (through inheritance) of $type. does is similar, but includes roles.
my = 17;say .isa("Int"); # OUTPUT: «True» say .isa(Any); # OUTPUT: «True» ;my = 0 but Truish;say .^name; # OUTPUT: «Int+{Truish}» say .does(Truish); # OUTPUT: «True» say .isa(Truish); # OUTPUT: «False»(Mu) routine does §
method does(Mu --> Bool)Returns True if and only if the invocant conforms to type $type.
my = Date.new('2016-06-03');say .does(Dateish); # True (Date does role Dateish) say .does(Any); # True (Date is a subclass of Any) say .does(DateTime); # False (Date is not a subclass of DateTime) Unlike isa, which returns True only for superclasses, does includes both superclasses and roles.
say .isa(Dateish); # OUTPUT: «False» Using the smartmatch operator ~~ is a more idiomatic alternative.
my = Date.new('2016-06-03');say ~~ Dateish; # OUTPUT: «True» say ~~ Any; # OUTPUT: «True» say ~~ DateTime; # OUTPUT: «False»(Mu) routine Bool §
multi sub Bool(Mu --> Bool)multi method Bool( --> Bool)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»(Mu) method Capture §
Declared as:
method Capture(Mu: --> Capture)Returns a Capture with named arguments corresponding to invocant's public attributes:
.new.Capture.say; # OUTPUT: «\(:bar("something else"), :foo(42))»(Mu) method Str §
multi method Str(--> Str)Returns a string representation of the invocant, intended to be machine readable. Method Str warns on type objects, and produces the empty string.
say Mu.Str; # Use of uninitialized value of type Mu in string context. my = [2,3,1];say .Str # OUTPUT: «2 3 1»(Mu) routine gist §
multi sub gist(+args --> Str)multi method gist( --> Str)Returns a string representation of the invocant, optimized for fast recognition by humans. As such lists will be truncated at 100 elements. Use .raku to get all elements.
The default gist method in Mu re-dispatches to the raku method for defined invocants, and returns the type name in parenthesis for type object invocants. Many built-in classes override the case of instances to something more specific that may truncate output.
gist is the method that say calls implicitly, so say $something and say $something.gist generally produce the same output.
say Mu.gist; # OUTPUT: «(Mu)» say Mu.new.gist; # OUTPUT: «Mu.new»(Mu) method perl §
multi method perl(Mu:)Calls .raku on the invocant. Since the change of the language name to Raku, this method is deprecated and might disappear in the near future. Use .raku instead.
(Mu) method raku §
multi method raku(Mu:)multi method raku(Mu:)For type objects, returns its name if .raku has not been redefined from Mu, or calls .raku on the name of the type object otherwise.
say Str.raku; # OUTPUT: «Str»For plain objects, it will conventionally return a representation of the object that can be used via EVAL to reconstruct the value of the object.
say (1..3).Set.raku; # OUTPUT: «Set.new(1,2,3)»(Mu) method item §
method item(Mu \item:) is rawForces the invocant to be evaluated in item context and returns the value of it.
say [1,2,3].item.raku; # OUTPUT: «$[1, 2, 3]» say %( apple => 10 ).item.raku; # OUTPUT: «${:apple(10)}» say "abc".item.raku; # OUTPUT: «"abc"»(Mu) method self §
method self(--> Mu)Returns the object it is called on.
(Mu) method clone §
multi method clone(Mu: *)multi method clone(Mu: *)This method will clone type objects, or die if it's invoked with any argument.
say Num.clone( :yes ) # OUTPUT: «(exit code 1) Cannot set attribute values when cloning a type object in block <unit>»
If invoked with value objects, it creates a shallow clone of the invocant, including shallow cloning of private attributes. Alternative values for public attributes can be provided via named arguments with names matching the attributes' names.
my = Point2D.new(x => 2, y => 3); say ; # OUTPUT: «Point(2, 3)» say .clone(y => -5); # OUTPUT: «Point(2, -5)» Note that .clone does not go the extra mile to shallow-copy @. and %. sigiled attributes and, if modified, the modifications will still be available in the original object:
my = Foo.new;with my = .clone # Hash and Array attribute modifications in clone appear in original as well: say ;# OUTPUT: «Foo.new(foo => 42, bar => ["Z", "Y"], baz => {:X("W"), :Z("Y")}, …» say ;# OUTPUT: «Foo.new(foo => 70, bar => ["Z", "Y"], baz => {:X("W"), :Z("Y")}, …» .boo.(); # OUTPUT: «Hi» .boo.(); # OUTPUT: «Bye» To clone those, you could implement your own .clone that clones the appropriate attributes and passes the new values to Mu.clone, for example, via nextwith.
my = Bar.new( :42quux );with my = .clone # Hash and Array attribute modifications in clone do not affect original: say ;# OUTPUT: «Bar.new(quux => 42, foo => ["a", "b"], bar => {:a("b"), :c("d")})» say ;# OUTPUT: «Bar.new(quux => 42, foo => ["Z", "Y"], bar => {:X("W"), :Z("Y")})» The |%_ is needed to slurp the rest of the attributes that would have been copied via shallow copy.
(Mu) method new §
multi method new(*)multi method new($, *@)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.
new triggers an object construction mechanism that calls submethods named BUILD in each class of an inheritance hierarchy, if they exist. See the documentation on object construction for more information.
(Mu) method bless §
method bless(* --> Mu)Low-level object construction method, usually called from within new, implicitly from the default constructor, or explicitly if you create your own constructor. bless creates a new object of the same type as the invocant, using the named arguments to initialize attributes and returns the created object.
It is usually invoked within custom new method implementations:
my = Point.new(-1, 1);In this example we are declaring this new method to avoid the extra syntax of using pairs when creating the object. self.bless returns the object, which is in turn returned by new. new is declared as a multi method so that we can still use the default constructor like this: Point.new( x => 3, y => 8 ).
For more details see the documentation on object construction.
(Mu) method CREATE §
method CREATE(--> Mu)Allocates a new object of the same type as the invocant, without initializing any attributes.
say Mu.CREATE.defined; # OUTPUT: «True»(Mu) method print §
multi method print(--> Bool)Prints value to $*OUT after stringification using .Str method without adding a newline at end.
"abc\n".print; # OUTPUT: «abc»(Mu) method put §
multi method put(--> Bool)Prints value to $*OUT, adding a newline at end, and if necessary, stringifying non-Str object using the .Str method.
"abc".put; # OUTPUT: «abc»(Mu) method say §
multi method say()Will say to standard output.
say 42; # OUTPUT: «42»What say actually does is, thus, deferred to the actual subclass. In most cases it calls .gist on the object, returning a compact string representation.
In non-sink context, say will always return True.
say (1,[1,2],"foo",Mu).map: so *.say ;# OUTPUT: «1[1 2]foo(Mu)(True True True True)»However, this behavior is just conventional and you shouldn't trust it for your code. It's useful, however, to explain certain behaviors.
say is first printing out in *.say, but the outermost say is printing the True values returned by the so operation.
(Mu) method ACCEPTS §
multi method ACCEPTS(Mu: )ACCEPTS is the method that smartmatching with the infix ~~ operator and given/when invokes on the right-hand side (the matcher).
The Mu:U multi performs a type check. Returns True if $other conforms to the invocant (which is always a type object or failure).
say 42 ~~ Mu; # OUTPUT: «True» say 42 ~~ Int; # OUTPUT: «True» say 42 ~~ Str; # OUTPUT: «False»Note that there is no multi for defined invocants; this is to allow autothreading of junctions, which happens as a fallback mechanism when no direct candidate is available to dispatch to.
(Mu) method WHICH §
multi method WHICH(--> ObjAt)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.
say 42.WHICH eq 42.WHICH; # OUTPUT: «True»(Mu) method WHERE §
method WHERE(--> Int)Returns an Int representing the memory address of the object. Please note that in the Rakudo implementation of Raku, and possibly other implementations, the memory location of an object is NOT fixed for the lifetime of the object. So it has limited use for applications, and is intended as a debugging tool only.
(Mu) method WHY §
multi method WHY(Mu: --> Pod::Block::Declarator)Returns the attached Pod::Block::Declarator.
For instance:
sub cast(Spell ) say .WHY;# OUTPUT: «Initiate a specified spell normally(do not use for class 7 spells)» See Pod declarator blocks for details about attaching Pod to variables, classes, functions, methods, etc.
(Mu) trait is export §
multi sub trait_mod:<is>(Mu \type, :!)Marks a type as being exported, that is, available to external users.
my is export A user of a module or class automatically gets all the symbols imported that are marked as is export.
See Exporting and Selective Importing Modules for more details.
(Mu) method return §
method return()The method return will stop execution of a subroutine or method, run all relevant phasers and provide invocant as a return value to the caller. If a return type constraint is provided it will be checked unless the return value is Nil. A control exception is raised and can be caught with CONTROL.
sub f ;say f(); # OUTPUT: «any(1, 2, 3)»(Mu) method return-rw §
Same as method return except that return-rw returns a writable container to the invocant (see more details here: return-rw).
(Mu) method emit §
method emit()Emits the invocant into the enclosing supply or react block.
react # OUTPUT: # received Str (foo) # received Int (42) # received Rat (0.5)(Mu) method take §
method take()Returns the invocant in the enclosing gather block.
sub insert(, +) say insert ':', <a b c>;# OUTPUT: «(a : b : c)»(Mu) routine take §
sub take(\item)Takes the given item and passes it to the enclosing gather block.
my = 6;my = 49;gather for ^ .say; # six random values(Mu) routine take-rw §
sub take-rw(\item)Returns the given item to the enclosing gather block, without introducing a new container.
my = 1...3;sub f();for f() ;say ;# OUTPUT: «[2 3 4]»(Mu) method so §
method so()Evaluates the item in Boolean context (and thus, for instance, collapses Junctions), and returns the result. It is the opposite of not, and equivalent to the ? operator.
One can use this method similarly to the English sentence: "If that is so, then do this thing". For instance,
my = <-a -e -b -v>;my = any() eq '-v' | '-V';if .so # OUTPUT: «Verbose option detected in arguments»The $verbose-selected variable in this case contains a Junction, whose value is any(any(False, False), any(False, False), any(False, False), any(True, False)). That is actually a truish value; thus, negating it will yield False. The negation of that result will be True. so is performing all those operations under the hood.
(Mu) method not §
method not()Evaluates the item in Boolean context (leading to final evaluation of Junctions, for instance), and negates the result. It is the opposite of so and its behavior is equivalent to the ! operator.
my = <-a -e -b>;my = any() eq '-v' | '-V';if .not # OUTPUT: «Verbose option not present in arguments»Since there is also a prefix version of not, this example reads better as:
my = <-a -e -b>;my = any() eq '-v' | '-V';if not # OUTPUT: «Verbose option not present in arguments»