method head

Documentation for method head assembled from the following types:

class Any

From Any

(Any) method head

Defined as:

multi method head(Any:D:is raw
multi method head(Any:D: Callable:D $w)
multi method head(Any:D: $n)

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)␤» 

class List

From List

(List) method head

Defined as:

multi method head(Any:D:is raw
multi method head(Any:D: Callable:D $w)
multi method head(Any:D: $n)

This method is directly inherited from Any, and it returns the first $n items of the list, an empty list if $n <= 0, or the first element with no argument. The version that takes a Callable uses a WhateverCode to specify all elements, starting from the first, but the last ones.

Examples:

say <a b c d e>.head ;     # OUTPUT: «a␤» 
say <a b c d e>.head(2);   # OUTPUT: «(a b)␤» 
say <a b c d e>.head(*-3); # OUTPUT: «(a b)␤» 

class Supply

From Supply

(Supply) method head

method head(Supply:D: Int(Cool$number = 1 --> Supply:D)

Creates a "head" supply with the same semantics as List.head.

my $s = Supply.from-list(41032);
my $hs = $s.head(2);
$hs.tap(&say);           # OUTPUT: «4␤10␤»