Basic Perl 6 LearnXinYminutes

perl6.html.markdown

@@ -0,0 +1,121 @@
+---
+name: perl6
+category: language
+language: perl6
+filename: learnperl6.pl
+contributors:
+    - ["Nami-Doc", "http://github.com/Nami-Doc"]
+---
+
+Perl 6 is a highly capable, feature-rich programming language made for the upcoming hundred years.
+
+Perl 6 runs on [the Parrot VM](http://parrot.org/), the JVM and [the MoarVM](http://moarvm.com).
+
+```perl6
+# Single line comment start with a pound
+
+#`(
+  Multiline comments use #` and a quoting construct. (), [], {}, 「」, etc, will work.
+)
+
+### Variables
+
+# In Perl 6, you declare a lexical variable using `my`
+
+# Perl 6 has 4 variable types :
+
+## - Scalars. They represent a single value. They start with a `$`
+
+my $str = 'String';
+my $str2 = "String"; # double quotes allow for interpolation
+
+# variable names can contain but not end with simple quotes and dashes, and can contain (and end with) underscores
+
+my $weird'variable-name_ = 5;
+
+## - Arrays. They represent multiple values. They start with `@`
+
+my @array = 1, 2, 3;
+my @array = 'a', 'b', 'c';
+# equivalent to :
+my @array = <a b c>; # similar to perl5's qw, or Ruby's %w
+
+say @array[2]; # Arrays are 0-indexed
+
+## - Hashes
+
+my %hash = 1 => 2,
+           3 => 4;
+my %hash = autoquoted => "key",
+            "some other" => "value", # trailing commas are okay
+            ;
+my %hash = <key1 value1 key2 value2> # you can also create a hash from an even-numbered array
+
+say %hash{'key1'}; # You can use {} to get the value from a key
+say %hash<key2>; # if it's a string, you can actually use <>
+
+## - Subs (subroutines, or functions in most other languages). Stored in variable, they use `&`
+sub say-hello { say "Hello, world" }
+
+# since you can omit parenthesis to call a function with no arguments, you need to use `&` also to capture `say-hello`
+my &s = &say-hello;
+my &other-s = sub { say "anonymous function !" }
+
+# `->`, lambda with arguments, and string interpolation
+my &lambda = -> $argument { "The argument passed to this lambda is $argument" }
+
+### Control Flow Structures
+
+# You don't need to put parenthesis around the condition, but that also means you always have to use brackets (`{ }`) for their body :
+
+## Conditionals
+
+if True {
+  say "It's true !";
+}
+
+unless False {
+  say "It's not false !";
+}
+
+# if (true) say; # Won't work
+
+# `given`-`when` looks like other languages `switch`, but it's much more powerful thanks to smart matching :
+given "foo bar" { # given just puts its argument into `$_`, and `when` uses it.
+  when /foo/ { # smart matching a string with a regex returns true if it matches
+    say "Yay !";
+  }
+  when $_.chars > 50 { # smart matching anything with True gives True, so you can also put "normal" conditionals
+    say "Quite a long string !";
+  }
+}
+
+## Looping constructs
+
+### - `loop` is an infinite loop if you don't pass it arguments, but can also be a c-style `for` :
+loop {
+  say "This is an infinite loop !";
+  last; # last breaks out of the loop, like the `break` keyword in other languages
+}
+
+loop (my $i = 0; $i < 5; $i++) {
+  next if $i == 3; # `next` skips to the next iteration, like `continue` in other languages.
+                   # Notice that you can also use postfix conditionals, loops, etc.
+  say "This is a C-style for loop !";
+}
+
+### - `for` - Foreaches an array
+for @array -> $variable {
+  say "I've found $variable !";
+}
+
+# default variable is $_
+for array {
+  say "I've got $_";
+}
+
+# Note - the "lambda" `->` syntax isn't reserved to for :
+if long-computation() -> $result {
+  say "The result is $result";
+}
+```