Using Docker

I know Raku is rather new an I did not want to bother with installations, so I though I'll go the modern way and use Docker. For this to work first you need to Download Docker Desktop.

Then I can run the following:

$ docker run --rm -it rakudo-star

This will download (for the first time when I run this) the rakudo-star image and then run it. The --rm tells Docker to remove the container once I am done with it. -it means to enter interactive mode.

Interactive Hello World

The interactive mode immediately lands us inside the Raku interactive shell (aka. REPL) using a single greater-than sign as the prompt. There I can type in:

> say "Hello World!"

and also

> "Hello World!".say

They both work.

Actually, because it is an interactive shell, it is enough to type in the string:

> "Hello World!"

dir

I was not sure what to do next so I fell back to my Python background and typed dir. (OK, I know that here I don't have to type in the parentheses for the function call to work.)

Actually I was surprised by the result:

> dir
("mnt".IO "bin".IO "proc".IO "sbin".IO "tmp".IO "usr".IO "media".IO "lib".IO "opt".IO "srv".IO "lib64".IO "etc".IO "root".IO "home".IO "var".IO "sys".IO "dev".IO "boot".IO "run".IO ".dockerenv".IO)

This is the content of the root directory of the Docker container.

shell

I am not sure what was I thinking but then I also tried to call shell and it worked!

shell("ls -l")

help

At this point I ran out ideas so I tried typing in help

===SORRY!=== Error while compiling:
Undeclared routine:
    help used at line 1

I guess there is no excuse. I'll have to find a tutorial and some documentation.

Version

Then I quite the interactive shell by typing exit.

$ docker run --rm rakudo-star raku -v
This is Rakudo version 2020.01 built on MoarVM version 2020.01.1
implementing Perl 6.d.

Hmm, that seems to be a bit old. I was under the impression that Rakudo Star is released every 3 months. I guess I was mistaken.

Hello World on the command line

$ docker run --rm rakudo-star raku -e 'say "Hello World!"'

Hello World in a file

I've created a file called hello_world.raku:

examples/raku/hello_world.raku

use v6;

say "Hello World";

"Hello Raku".say;

Then ran it as:

docker run --rm -v $(pwd):/opt rakudo-star raku /opt/hello_world.raku

The -v $(pwd):/opt parameter tells Docker to map the current directory on my own computer to the /opt directory inside the Docker image. Then on the command line I passed in

raku /opt/hello_world.raku

That will execute the given file and I got:

Hello World
Hello Raku

Great, so things are working quite smoothly. It is time to dig out my old course material and see what still works and what I need to improve.

If you are interested in Docker I have a Docker course