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Welcome to Shelly

Shelly is a Unix shell with a typed scripting language. Run familiar programs, then use functions, collections, and application types to work with their data. A pipeline can carry a String, an Integer, or a whole record between Shelly stages; external programs still communicate through ordinary byte streams.

Start with a pipeline

Suppose a game awards three points for each completed challenge:

let $completed = [2, 5, 8]
let $points: [Integer]
$completed | ($ * 3) | $points
echo $points...

6 15 24

The source supplies one item at a time. $ is that item's value, ($ * 3) is a stage expression, and the final variable collects the answers. The source and answers are typed values throughout. Pipelines explains how this extends to processes, conversions, and streams.

Pipeline splits let the same upstream stream feed several paths. Aligned connectors show which stage supplies each branch, so you can transform or collect each path independently without running the source again.

Choose a route

I want to…	Start here
Try Shelly in a few minutes	Quick start
Run scripts or use it as my shell	Running Shelly
Understand the language as a whole	Language map
Process structured data	Arrays, Hash maps, Pipelines
Send one stream down several paths	Pipeline splits
Build reusable application code	Functions, Structs, Modules
Work with files and services	Bytes and I/O, JSON, HTTP
Customize my terminal	REPL, Prompts and widgets
Find a complete small example	Recipes
Look up punctuation or a declaration	Syntax reference

A few conventions

Variables begin with $. Commands take space-separated arguments. Braces contain statements, and # starts a comment. Use echo to show a value: entering an expression alone does not automatically print it.

Type names are case-sensitive: Integer, Float, String, and any. Numeric annotations widen Integers to Float when required. Distinct named types give application concepts their own identities.

let $answer = calculate calls calculate. Quote text to keep it as text. A backtick creates a checked callable reference without calling it.

Project and documentation

Shelly runs on Linux, WSL, and macOS. Its core language is implemented; the project is in stabilization while the prototype's internals are reviewed for future cleanup. These pages describe the current language and public library interfaces.

Source and releases · Installation and execution modes · VS Code support

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Related: Language map · Quick start