Which has a greater airspeed velocity... an unladen swallow or Santa's sleigh?

Well, that depends... are we talking about an African or European swallow?

Welcome to Day 21 of the YAMLScript Advent Blog!

So far we've been using the YAMLScript CLI ys to run (or load) our YAMLScript programs. YAML users are used to using a YAML framework module inside their programs. For example, in Python you might do:

import yaml

yaml_text = """
- 40
- 50
- 60
"""

data = yaml.safe_load(yaml_text)

print(data)
# => [40, 50, 60]

Wouldn't it be nice if we could do the same thing in YAMLScript? As of today, we can!

import yamlscript

yaml_text = """
- 40
- 50
- 60
"""

data = yamlscript.load(yaml_text)

print(data)
# => [40, 50, 60]

The only thing that changed was the name of the module.

But this module has super powers.

import yamlscript

yaml_text = """
!yamlscript/v0
mapv \(% * 10): 4..6
"""

data = yamlscript.load(yaml_text)

print(data)
# => [40, 50, 60]

We can use YAMLScript functions in our YAML text to generate or manipulate data.

That example was a bit contrived, but I just wanted to show how easy it is to load plain old YAML or super powered YAML with the new yamlscript Python module.

Here's an example that might be more exciting.

Say we have this normal YAML file with some data in it:

# db.yaml
cars:
- make: Ford
  model: Mustang
  year: 1967
  color: red
- make: Dodge
  model: Charger
  year: 1969
  color: orange
- make: Chevrolet
  model: Camaro
  year: 1969
  color: blue

We could have another YAML file that uses YAMLScript:

# racers.yaml
!yamlscript/v0

db =: load("db.yaml")

=>: !
- name: Ingy döt Net
  car: ! db.cars.0
- name: Santa Claus
  car: ! db.cars.1
- name: Sir Lancelot
  car: ! db.cars.2

Then we could load the data into Python and print it out:

# race-report.py
import yaml, yamlscript

data = yamlscript.load('racers.yaml')

print(yaml.dump(data))

And we get:

- car:
    color: red
    make: Ford
    model: Mustang
    year: 1967
  name: Ingy dot Net
- car:
    color: orange
    make: Dodge
    model: Charger
    year: 1969
  name: Santa Claus
- car:
    color: blue
    make: Chevrolet
    model: Camaro
    year: 1969
  name: Sir Lancelot

Pretty cool, huh?

There's no end to the things you can do with this.

Today we're showing off the Python YAMLScript module but soon this module will be available in every language that has a need for it.

Installing the yamlscript Python Module

Normally to install a Python module you would do:

pip install a-python-module

With YAMLScript, you do the same:

pip install yamlscript

But you also need to install the libyamlscript shared library.

You can do that with:

curl https://yamlscript.org/install | bash

That will install the latest version of libyamlscript for your platform in /usr/local/lib. You'll need to have root access to do this.

If you want to install it somewhere else, you can set the PREFIX option:

curl https://yamlscript.org/install | PREFIX=~/ys bash

But then you'll need to set the LD_LIBRARY_PATH environment variable to point to it:

export LD_LIBRARY_PATH=~/ys/lib

Eventually we may package the yamlscript.py module with wheels (binary assets) for libyamlscript, but for now you'll need to install it yourself.

If you're a polyglot like me, at least you only have to install it once. :- )

The Holy Graal

This magic is all possible because of the GraalVM project. Not only does GraalVM's native-image tool compile to binary executables, it also can compile to shared libraries.

YAMLScript generates and publishes the libyamlscript shared library and then offers binding modules for it in many languages.

I hope you are starting to see the power of YAMLScript. Not only as a new programming language, but also as a new way to work with YAML files that you already have.

Join me tomorrow for Day 22 of the YAMLScript Advent Blog!