yaml / yamlscript
YAMLScript PHP binding - Program in YAML — Code is Data
Requires
- php: >=7.4
- ext-ffi: *
Requires (Dev)
- phpunit/phpunit: ^9.5
- squizlabs/php_codesniffer: ^3.7
README
YAMLScript
Add Logic to Your YAML Files
Quick Start
This library lets you load YAML files that may or may not contain YAMLScript functional programming logic. You can use it as a drop-in replacement for your current YAML loader.
Here's an example config.yaml
that makes use of YAMLScript functions.
# config.yaml with YAMLScript: !YS-v0: # Define variables db-host =: ENV.DB_HOST || 'localhost' db-port =: ENV.DB_PORT || 5432 deploy =: ENV.DEPLOYMENT || 'dev' :when deploy !~ /^(dev|stage|prod)/: die: | Invalid deployment value '$deploy'. Must be one of: dev | stage | prod # Normal YAML data description: Dynamic application configuration # Dynamic data values database: host:: db-host port:: db-port:num name:: "app_$deploy" # Import external data features:: load('common.yaml').features # Use logic and conditions cache: # Variable scoped to this mapping enabled =: deploy == 'production' directory: .cache enabled:: enabled limit: 100 # Conditional key/value pairs :when enabled:: limit:: 1000 ttl:: 60 * 60 # 3600
What is YAMLScript?
YAMLScript is a functional programming language that can be embedded in YAML. Its syntax is 100% YAML so files that embed it are still valid YAML files.
The YAMLScript project provides YAML loader libraries for many programming languages. They can be used to load any YAML config files properly, whether or not they contain functional programming logic.
It's perfect for:
- Configuration files that need logic, variables, and dynamic values
- Data transformation with built-in functions for JSON, YAML, and text processing
- Templating with powerful string interpolation and data manipulation
- Scripting as a complete functional programming language
Key Features
- Drop-in YAML replacement – Works with your existing YAML files
- Variables & functions – Define and reuse values throughout your files
- External data loading – Import JSON, YAML, or data from URLs
- Conditional logic – Use if/then/else and pattern matching
- Data transformation – Built-ins for transforming & manipulating data
- String interpolation – Embed expressions/variables directly in strings
- No JVM required – Runs as a native library despite compiling to Clojure
How It Works
YAMLScript extends YAML with a simple, elegant syntax:
# file.yaml !YS-v0: # Enable YAMLScript name =: 'World' # Variable assignment nums =:: [1, 2, 3] # Any YAML value # Literal YAML with ':' a key: a value # Evaluated expressions with '::' message:: "Hello, $name!" sum:: nums.reduce(+) timestamp:: now():str
You can load this file from a program as described below, or you can use the
ys
YAMLScript binary to load the file from the command line:
$ ys -Y file.yaml a key: a value message: Hello, World! sum: 6 timestamp: '2025-09-14T22:35:42.832470203Z'
Under the hood, YAMLScript compiles YAML to Clojure and evaluates it, giving you access to a rich functional programming environment.
PHP Usage
Use yamlscript
as a drop-in replacement for your current YAML loader:
<?php // program.php require_once 'vendor/autoload.php'; use YAMLScript\YAMLScript; $ys = new YAMLScript(); // Load from file $input = file_get_contents('config.yaml'); $config = $ys->load($input); echo json_encode($config, JSON_PRETTY_PRINT); ?>
Installation
Install YAMLScript for PHP and the libys.so
shared library:
# Install via Composer composer require yaml/yamlscript # Install shared library curl -sSL https://yamlscript.org/install | bash
See https://yamlscript.org/doc/install/ for more info.
Requirements
- PHP 8.3 or higher
See Also
- YAMLScript Web Site
- Learn YAMLScript
- YAMLScript Blog
- YAMLScript Source Code
- YAMLScript Programs
- YAML
- Clojure
Authors
Authors
- Ingy döt Net
License & Copyright
Copyright 2022-2025 Ingy döt Net ingy@ingy.net
This project is licensed under the terms of the MIT
license.
See LICENSE for more
details.