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Jac Docs

Welcome

Welcome to Jac

Section titled “Welcome to Jac”

One Language for AI-Native Full-Stack Development

Jac is a programming language that supersets Python and JavaScript with native compilation support, adding novel constructs for AI-integrated programming. Access the entire PyPI and npm ecosystems while using features like by llm() to seamlessly weave AI into your code. Write backend logic, frontend interfaces, and AI integrations in a single unified language.

Why Jac?

Section titled “Why Jac?”
What You WantHow Jac Helps
Build AI apps easilyNative LLM integration with by llm() - no prompt engineering
Full-stack in one languageReact-style frontend + Python backend, seamlessly connected
Use existing librariesFull access to PyPI and npm ecosystems
Deploy without DevOpsjac start --scale deploys to Kubernetes automatically
Model complex domainsGraph-based Object-Spatial Programming for connected data
Code with AI assistanceClean syntax designed for both humans and AI models to read and write

Get Started in 5 Minutes

Section titled “Get Started in 5 Minutes”

Step 1: Install

Section titled “Step 1: Install”
pip install jaseci

This installs the complete Jac ecosystem: jaclang (compiler), byllm (AI integration), jac-client (frontend), jac-scale (deployment), and jac-super (enhanced console).

Verify your installation:

jac --version

This also warms the cache, making subsequent commands faster.

Step 2: Create Your First Program

Section titled “Step 2: Create Your First Program”

Create hello.jac:

with entry {
    print("Hello from Jac!");
}

Step 3: Run It

Section titled “Step 3: Run It”
jac hello.jac

Note: jac is shorthand for jac run - both work identically.

That’s it! You just ran your first Jac program.

Choose Your Path

Section titled “Choose Your Path”

Just want to try it?

Section titled “Just want to try it?”

Follow the Hello World guide to write your first program in 2 minutes.

Building a web app?

Section titled “Building a web app?”

Jump to Build Your First App - build a complete app with a 3-part tutorial.

Working with AI/LLMs?

Section titled “Working with AI/LLMs?”

See the AI Integration tutorial for byLLM basics, or try Part 2: Add AI in the first app tutorial.

Want the full picture?

Section titled “Want the full picture?”

Read Next Steps for learning paths by experience level.

Core Principles

Section titled “Core Principles”

Jac is built on six key principles:

  1. AI-Native - LLMs as first-class types via Meaning Typed Programming. Call AI like a function.

  2. Full-Stack in One Language - Write React components alongside server code. No context switching.

  3. Supersets Python & JavaScript - Use numpy, pandas, react, tailwind directly. Your existing knowledge applies.

  4. Object-Spatial Programming - Model domains as graphs. Deploy walkers to traverse and transform data.

  5. Cloud-Native - One command to production: jac start --scale handles Kubernetes, Redis, MongoDB.

  6. Human + AI Readable - Clean syntax that both developers and AI models can read and write effectively.

Who is Jac For?

Section titled “Who is Jac For?”

Jac is designed for developers who want to build AI-powered applications without the complexity of managing multiple languages and tools.

You AreJac Gives You
Startup FounderBuild and ship complete products faster with one language
AI/ML EngineerNative LLM integration without prompt engineering overhead
Full-Stack DeveloperReact frontend + Python backend, no context switching
Python DeveloperFamiliar syntax with powerful new capabilities
Frontend EngineerWrite UI components with full access to npm ecosystem
Student/LearnerModern language designed for clarity and simplicity

When to Use Jac

Section titled “When to Use Jac”

Jac excels at:

  • AI-powered applications with LLM integration
  • Full-stack web applications (frontend + backend)
  • Applications with complex relational data (graphs, networks)
  • Rapid prototyping with production scalability
  • Projects requiring both Python and JavaScript ecosystems

Consider alternatives for:

  • Performance-critical systems programming (use Rust, C++)
  • Mobile native apps (use Swift, Kotlin)
  • Simple scripts where Python suffices
Section titled “Quick Links”
ResourceDescription
InstallationDetailed setup with IDE configuration
Hello WorldYour first Jac program (2 min)
Build Your First AppComplete 3-part tutorial: todo app, AI, walkers
TutorialsIn-depth learning paths
Language ReferenceComplete language documentation
CLI ReferenceAll jac commands

Need Help?

Section titled “Need Help?”