Rosetta Code

by Ingy döt Net | | 3 min read

How does Santa read all the signs in all the languages of the world? That's a lot of languages to know on top of all the other things he has to do. Luckily he has his trusty polyglot elf, Rosetta, at his side. Bet you didn't know that!

Welcome to Day 17 of the YAMLScript Advent Calendar

A cool guy named Mike Mol made a website called Rosetta Code for programmers who want to learn all the programming languages of the world!

It's a wiki that has well over 1000 programming tasks and almost 1000 programming languages. The idea is for people to contribute solutions to the tasks in as many languages as they can.

I've been a fan of Rosetta Code for years. Here's one of my all time favorite programs from the site: FizzBuzz in SNUSP!!

One thing people like to use Rosetta Code for is to show off a new language. YAMLScript is a new language, and I've put a few solutions up there myself:

Adding solutions to Rosetta Code is a one of the best ways I've found to figure out what YAMLScript needs to do and what it needs to do better.

Rosetta Code Data

The Rosetta Code website is a great resource, but it's a bit clunky to use. It would be really cool if all the code examples were available in a nice Git repository.

Well, it turns out that they are! You can clone over 100,000 code examples in a few seconds by running this command:

$ git clone https://github.com/acmeism/RosettaCodeData
$ cd RosettaCodeData
$ ls -l Lang/YAMLScript/
total 8
00-LANG.txt
00-META.yaml
99-bottles-of-beer -> ../../Task/99-bottles-of-beer/YAMLScript/
Factorial -> ../../Task/Factorial/YAMLScript/
Fibonacci-sequence -> ../../Task/Fibonacci-sequence/YAMLScript/
FizzBuzz -> ../../Task/FizzBuzz/YAMLScript/
Hello-world-Text -> ../../Task/Hello-world-Text/YAMLScript/

The Rosetta Code Data Project is something I wrote almost 15 years ago. This last summer I was able to make it a lot easier to update.

Let's try out the FizzBuzz example:

$ ys Task/FizzBuzz/YAMLScript/fizzbuzz.ys 16
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16

Pretty cool, huh?

RC Needs More YS!

Let's try adding a new YAMLScript solution to Rosetta Code.

The first thing to do is to find a task that doesn't have a YAMLScript solution yet. You can find all the tasks listed here.

Let's take the first one: 100 doors.

What I like to do next is cheat! Clojure has solved most of the tasks on Rosetta Code, and YAMLScript is another way to write Clojure, so let's just pick a Clojure solution and translate it to YAMLScript.

(defn doors []
	(reduce (fn [doors idx] (assoc doors idx true))
	        (into [] (repeat 100 false))
	        (map #(dec (* % %)) (range 1 11))))

(defn open-doors [] (for [[d n] (map vector (doors) (iterate inc 1)) :when d] n))

(defn print-open-doors []
  (println
    "Open doors after 100 passes:"
    (apply str (interpose ", " (open-doors)))))

(print-open-doors)

Here's a quick translation to YAMLScript:

!yamlscript/v0

defn doors():
  reduce:
    fn [doors idx]: assoc(doors idx true)
    into []: repeat(100 false)
    map \(dec (% * %)): (1 .. 10)

defn open-doors():
  for: .[[d n] map(vector doors() iterate(inc 1)) :when d] n

defn print-open-doors():
  say:
    "Open doors after 100 passes:
    $(apply str interpose(\", \" open-doors()))"

=>: print-open-doors()

Let's see if it works:

$ ys 100-doors.ys
Open doors after 100 passes: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100

Great! Now let's clean it up a bit:

I'm just going to rename the print-open-doors function to main and move it to the top of the file. The main function (if defined) is called automatically when the script is run.

!yamlscript/v0

defn main():
  say:
    "Open doors after 100 passes:
    $(apply str interpose(\", \" open-doors()))"

defn open-doors():
  for: .[[d n] map(vector doors() iterate(inc 1)) :when d] n

defn doors():
  reduce:
    fn [doors idx]: assoc(doors idx true)
    into []: repeat(100 false)
    map \(dec (% * %)): 1..10

I also ordered the functions top-down in the order they are called since we know that YAMLScript will auto-declare them in the generated Clojure code.

$ time ys 100-doors.ys
Open doors after 100 passes: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100

real    0m0.041s

Still works! Pretty fast too! Let's add it to Rosetta Code!

To do this you need to create an account on the site, login, and then click the "Edit" tab on the task page. It's a pretty terrible plain text editor, but scroll way down to where the YAMLScript solutions should go and add this:

=={{header|YAMLScript}}==
<syntaxhighlight lang="yaml">
!yamlscript/v0

defn main():
  say:
    "Open doors after 100 passes:
    $(apply str interpose(\", \" open-doors()))"

defn open-doors():
  for: .[[d n] map(vector doors() iterate(inc 1)) :when d] n

defn doors():
  reduce:
    fn [doors idx]: assoc(doors idx true)
    into []: repeat(100 false)
    map \(dec (% * %)): 1..10
</syntaxhighlight>
{{out}}
<pre>
$ ys 100-doors.ys
Open doors after 100 passes: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
</pre>

Click "Save changes" and you're done!

We did it!

Don't wait for me to add more YAMLScript solutions to Rosetta Code. You can do it yourself! If you do, send me (@ingydotnet) a DM on the Rosetta Code Discord server and I'll update the Rosetta Code Data Project repo with your solutions.

If you had never heard of Rosetta Code before, I hope you'll find it as interesting as I do.

Check back tomorrow for Day 18 of the YAMLScript Advent Calendar!