Raku by Example: Hello World!

Comments

Raku supports both single line and multi-line comments. Use a pound (#) symbol for single line comments and #`, followed by a bracketing construct ((), [], {}, etc.) for multi-line comments. The same syntax for multi-line comments can be used for embedded comments.

# This is a single line comment.

#`{
This is a multiline comment and I 
can write as many lines as I want.
This is another line.
}

for #`(each letter in) 'a'..'c' {
    say #`(it to the terminal; that's) $_;
    #`[The Old Wise called it literate programming. jk!]
}

$ perl6 comments.p6
a
b
c

Hello world!

Raku has several ways outputting text to the terminal. Some of the most noteworthy are:

• print - prints to standard output and coerces non-string objects to strings (Str) by calling the method .Str on them. It doesn't add a trailing newline to its output.

• put - similar to print but adds a trailing newline to its output by calling print-nl on its argument.

• say - similar to put but uses the .gist method to print the string representation of a given object.

• note - similar to say but it prints to standard error instead. It prints "Noted" if no arguments are passed to its subroutine form.

print "Hello, world!\n"; # Or: print("Hello, world!");
say   "Hello, world!";   # Or: say("Hello, world!");
put   "Hello, world!";   # Or: put("Hello, world!");
note  "Hello, world!";   # Or: note("Hello, World!");
note;                    # No argument passed so it prints "Noted" to STDERR.

# Or in a more object oriented manner:
"Hello, world!\n".print;
"Hello, world!".put;
"Hello, world!".say;
"Hello, world!".note;

$ perl6 hello-world.p6

STDOUT:

Hello, world!
Hello, world!
Hello, world!
Hello, world!
Hello, world!
Hello, world!

STDERR:

Hello, world!
Noted
Hello, world!