6 things about perl 6

6 things
about 6
NY.pm, 8 Dec 2016

ThePerlReview•www.theperlreview.com
6ThingsAbout6
perlmodules.net

6ThingsAbout6
Phasers

6ThingsAbout6
count = 0;
while ( … ) {
…
}
output "There were {count} items!";

6ThingsAbout6
use v6;
while( … ) {
state $count = 0;
LAST { put "There were $count" }
…
}

6ThingsAbout6 # Program execution
BEGIN { put "BEGIN, at compile time, ASAP" }
CHECK { put "CHECK, at compile time, ALAP" }
INIT { put "INIT, during main execution, ASAP" }
END { put "END, during main execution, ALAP" }
for 0 .. 3 -> $item {
my Int $square = $item ** 2;
# Block phasers
ENTER { put "tENTER block" }
LEAVE { put "tLEAVE block" }
KEEP { put "KEEP block: Got value $_" } # NYI
UNDO { put "ttUNDO block" }
PRE { put "PRE block ------" }
POST { put "POST block" }
# Loop phasers
FIRST { put "tFIRST loop" }
NEXT { put "tNEXT loop" }
LAST { put "tLAST loop"; put "**** LOOP is done ****" }
}
https://www.learningperl6.com/2016/11/30/quick-tip-15-phasers/

6ThingsAbout6
Sets

6ThingsAbout6
$ perl6
> my $set = set( qw/ 5 cat dog 37 / )
set(37, 5, cat, dog)
> "5" ∈ $set
True
> 5 ∈ $set
False
> "5" (elem) $set
True

6ThingsAbout6
$ perl6
> my $set_a = set qw/ a b c /;
set(a, c, b)
> my $set_b = set qw/ c d e /;
set(c, e, d)
> $set_a ∪ $set_b
set(a, c, b, e, d)
> $set_a ∩ $set_b
set(c)
> $set_a ∖ $set_b
set(a, b)
> $set_a ⊖ $set_b
set(a, b, e, d)

6ThingsAbout6
Sequences

6ThingsAbout6
1, 2 … 10 # 1 to 10
1, 3 … 10 # odds
1, 5 … 10 # 1,5,9
1, 2 … * # infinite, lazy
1, 3 … * # odds
1, 5 … * # 1,5,9
1, 1, -> $n,$m {$n+$m} … *
1, 1, { $^a + $^b } … *
1, 1, * + * … *

6ThingsAbout6
Types

6ThingsAbout6
> my Int $i = 137
137
> my Int $j = 22/7
Type check failed in assignment to $j;
expected Int but got Rat (<22/7>)

6ThingsAbout6
> my Int @array = ( 1, 2, 3, 4 )
[1 2 3 4]
> my Int @array = qw/ 1 2 3 4 /
Type check failed in assignment to @array;
expected Int but got Str ("1")

6ThingsAbout6
> my Int %hash{Str}
{}
> %hash{ "Butterflies" } = 137
137
> %hash{ "Llamas" } = "Huh?"
Type check failed in binding to assignval;
expected Int but got Str ("Huh?")
> %hash{ 5 } = 1
Type check failed in binding to key;
expected Str but got Int (5)

6ThingsAbout6
my package EXPORT::DEFAULT {
...
subset Pos of Real where * > 0;
subset Neg of Real where * < 0;
subset Zero of Real where * == 0;
subset UNumeric of Real where * >= 0;
subset Even of Int where * % 2 == 0;
subset Odd of Int where * % 2;
}
https://github.com/bradclawsie/Subsets-Common

6ThingsAbout6
subset ZInt of Cool is export where {
state ( $min, $max ) =
%names.keys.sort( { $^a <=> $^b } ).[0,*-1];
( $_.truncate == $_ and $min <= $_ <= $max )
or
note "Expected a known atomic number between $min and $max"
and
False;
};
https://github.com/briandfoy/perl6-chemistry-elements

6ThingsAbout6
MAIN

6ThingsAbout6
sub MAIN ( $n, $m ) {
put "N: $n M: $m";
}
$ perl6 main.p6
Usage:
main.p6 <n> <m>

6ThingsAbout6
sub MAIN ( $n, $m = 5 ) {
put "N: $n M: $m";
}
$ perl6 main.p6
Usage:
main.p6 <n> [<m>]

6ThingsAbout6
sub MAIN ( Int $n, Int $m ) {
put "N: $n M: $m";
}
sub MAIN (
Int $n where * > 0,
Int $m where * < 0
) {
put "N: $n M: $m";
}

6ThingsAbout6
multi MAIN (
Int $n where * > 0,
Int $m where * < 0
) {
put "PosNeg => N: $n M: $m";
}
multi MAIN (
Int $n where * > 0,
Int $m where * > 0
) {
put "PosPos => N: $n M: $m";
}

6ThingsAbout6
Grammars

6ThingsAbout6
grammar Legal::Module::Name
{
token TOP
{
^ <identifier> [<separator><identifier>] ** 0..* $
}
token identifier
{ # leading alpha or _ only
<[A..Za..z_]>
<[A..Za..z0..9]> ** 0..*
}
token separator
{
:: # colon pairs
}
}
my $match_obj = Legal::Module::Name.parse($s);
http://perltricks.com/article/144/2015/1/13/How-to-create-a-grammar-in-Perl-6/

6ThingsAbout6
Questions

6 things about perl 6

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (10)

Similar to 6 things about perl 6

Similar to 6 things about perl 6 (20)

More from brian d foy

More from brian d foy (9)

Recently uploaded

Recently uploaded (20)

6 things about perl 6