Perl 6
Amazing Perl 6: Revision 11
This page lists some amazing Perl 6 snippets. The list after the title refers to the keywords for the snippet.
^ Factorial
* custom operators
* reduce operator
* range operator
* placeholder variable
.pre
sub postfix:<!> { [*] 1..$^n }
say 5!;
.pre
^^ Explanation
^^^ Custom Operators
There is a set of special sub declarations that interfere in the parsing of the language, these are the:
* prefix
* postfix
* circumfix
* infix
* postcircumfix
you declare them by using type:identifier, where the identifier is quoted using the '<' and '>', optionally « » when you want to use '<' or '>' as part of the identifier. Some examples of subs that come defined in Perl 6 core are:
* prefix:<^> which is the operator that turns ^100 into 0..99
* postfix:<i> which allows you to use complex numbers as in 1 + 2i
* circumfix:<( )> which creates a unflattened capture as in (1,2,(3,4,(5,6)))
* infix:<+> which sums two values, as in 1 + 2
* postcircumfix:<{ }> which is used as the hash subscript as in %a{$b}
So when you declare a sub postfix:<!> you are declaring a language operator that lives in the same level as any other Perl 6 operator.
^ Gather/Take
* gather/take
* lazy lists
* bind
.pre
my @a := gather for 1..1000 -> $i { say $i; take $i };
say @a[10]; # prints 1 2 3 4 5 6 7 8 9 10
.pre
^ Factorial
* custom operators
* reduce operator
* range operator
* placeholder variable
.pre
sub postfix:<!> { [*] 1..$^n }
say 5!;
.pre
^^ Explanation
^^^ Custom Operators
There is a set of special sub declarations that interfere in the parsing of the language, these are the:
* prefix
* postfix
* circumfix
* infix
* postcircumfix
you declare them by using type:identifier, where the identifier is quoted using the '<' and '>', optionally « » when you want to use '<' or '>' as part of the identifier. Some examples of subs that come defined in Perl 6 core are:
* prefix:<^> which is the operator that turns ^100 into 0..99
* postfix:<i> which allows you to use complex numbers as in 1 + 2i
* circumfix:<( )> which creates a unflattened capture as in (1,2,(3,4,(5,6)))
* infix:<+> which sums two values, as in 1 + 2
* postcircumfix:<{ }> which is used as the hash subscript as in %a{$b}
So when you declare a sub postfix:<!> you are declaring a language operator that lives in the same level as any other Perl 6 operator.
^ Gather/Take
* gather/take
* lazy lists
* bind
.pre
my @a := gather for 1..1000 -> $i { say $i; take $i };
say @a[10]; # prints 1 2 3 4 5 6 7 8 9 10
.pre
