Apple Pkl: A New Programming Language for Configuration

Apple introduces Pkl, a pioneering programming language for easier system configuration

In software development, configuration is a frequent and crucial process that lets engineers alter the look and feel of their environments, systems, and applications. Configuration, however, may also be difficult since it frequently entails creating intricate and prone-to-mistake code, handling many formats and languages, and guaranteeing data confidentiality and integrity. 

Apple has launched Pkl, a new programming language for configuration that is open-source, to solve these issues. Pkl programming language has a clear vocabulary, robust validation, and adaptable tooling intended to make setup simple and scalable. This article will outline Pkl's key attributes, discuss its advantages, and provide some instances of its application for various configuration chores.

What is Pkl?

Apple Pkl is a  programming language, which implies that instead of emphasizing the processes involved in achieving a goal, it describes the intended state of a system. Pkl is built on a key-value format that is comparable to JSON but has a few improvements, like:

• Type safety: Pkl supports both complicated kinds (like lists, maps, sets, and enums) and primitive types (like integers, strings, booleans, and null). Additionally, users may do type checking and validation at build time and runtime, as well as construct new types and schemas using Pkl.
• Expressiveness: Pkl allows users to write simple and dynamic configuration code by supporting variables, functions, operators, and control structures. Interpolation is another feature that Pkl offers, enabling users to insert expressions within strings.
• Modularity: Modules are supported by Pkl, enabling users to arrange and share configuration code among various projects and contexts. To allow users to access other resources and libraries, Pkl also allows imports and exports.
• Security: Sandboxing, which restricts the environment in which configuration code may be accessed and executed, is supported by Pkl. The least privilege option, which gives the bare minimum of permissions needed for a configuration job, is likewise supported by Pkl.

Why Use Pkl?

Pkl is intended to be a general-purpose and flexible programming language for configuration that may be applied to a variety of situations, including:

• Infrastructure: Networks, servers, cloud services, containers, and other infrastructure elements may all be configured using Pkl. Pkl is also capable of producing configuration files in XML, JSON, YAML, and property lists, among other forms.
• Applications: Pkl is a tool for configuring user interfaces, features, preferences, and program settings. Additionally, configuration code in several languages, including Java, Kotlin, Swift, and Go, may be generated by Pkl.
• Environments: Staging, production, testing, and development environments may all be configured with Pkl. Claims, environment variables, and credentials can also be generated using Pkl.

How to Use Pkl?

Pkl can be utilized as an embedded library or as a stand-alone utility. Users must install the Pkl command line interface (CLI), which is compatible with Linux, macOS, Alpine Linux, and Java, to use Pkl as a standalone program. Users may create, modify, build, execute, and test Pkl configuration files using the Pkl CLI. Users must add the Pkl dependency to their project and utilize the Pkl API to communicate with Pkl configuration files to use Pkl as an embedded library. The Pkl API allows for the reading, writing, verifying, and execution of Pkl configuration files and is available for Java, Kotlin, Swift, and Go.

The Pkl documentation offers a thorough installation guide, a language reference, examples, and release notes to help users get started with Pkl. The Pkl GitHub repository, which has the source code, discussions, pull requests, issues, and projects of Pkl, is another option for users to access. Additionally, users may help Pkl improve by reporting issues, making feature suggestions, uploading patches, and being involved in the community.