YAMLScript is a new approach to providing the extra capabilities that YAML users have been asking for (or adding themselves) for years. YAMLScript embeds cleanly into existing YAML files and adds new capabilities such as:

• Getting data from other YAML files
• Assigning variables
• Referencing other parts of YAML (without anchorsi/aliases)
• Interpolating variables and function calls into strings
• Transforming data structures
• Defining and calling functions
• Using external libraries
• Running shell commands
• And much more...

All of YAMLScript is (and must be) valid YAML syntax, even though it might seem surprising from time to time. Also all YAML config files are valid YAMLScript files and YAMLScript will treat them as such (no code execution), unless you explicitly tell it to do more (by adding a !yamlscript/v0 tag to the start).

!yamlscript/v0
say: "Welcome to YAMLScript!"

YAMLScript is also a complete, mature, functional, performant programming language. That's because under the hood, YAMLScript code is compiled to Clojure code and evaluated by a Clojure runtime. For most day to day YAMLScript use, you won't need to know anything about Clojure, but when you need to do something more advanced, all of Clojure is available for you to use.

Even though Clojure is a Lisp, YAMLScript code looks a lot more like Python, Ruby, Perl or JavaScript. And even though Clojure is a JVM (Java) language, YAMLScript doesn't use the JVM at all. YAMLScript is a fast standalone native binary, as is the libyamlscript shared library that it is used by all YAMLScript loader libraries.