Pyrefly Type Challenge — PyCon US 2026

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   ~~~ PyCon US 2026 Type Challenge ~~~
      May 13–19, 2026 · Long Beach, CA

Hello and welcome to the Pyrefly Type Challenge! Fix type bugs, configure Pyrefly, and write some type-safe code. Complete all three parts and show your work to Meta booth staff for a swag reward!

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What You'll Do:

Part	Task
1	Install & configure Pyrefly
2	Fix every type error in challenge.py
3	Write 20–50 lines of your own type-safe code

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Part 1: Setup

# 1. Clone the repo
git clone https://github.com/migeed-z/pyrefly-type-challenge.git
cd pyrefly-type-challenge

# 2. Install pyrefly (use any Python environment you prefer)
pip install pyrefly

# 3. Try running pyrefly on the challenge file
pyrefly check challenge.py

Now create a pyrefly.toml configuration file. Some bugs in challenge.py only show up when you enable error checks that Pyrefly doesn't turn on by default. Check the pyrefly docs to learn more.

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Part 2: Fix the Type Bugs

Open challenge.py and fix every type error. The file has a mix of bugs:

• Some that Pyrefly catches by default
• Others that only appear once your pyrefly.toml is configured correctly

Some fixes only need annotation changes, others require fixing the code itself — you can either rewrite the code or use error suppressions.

The rules:

• No Any — remove all uses of it
• pyrefly check challenge.py must pass with zero errors
• Don't delete functions — fix them!

Hint: there are 3 error kinds disabled by default that enable stricter checking for return types, parameter types, and decorators. And remember the "no Any" rule — there's a config setting for that too. Check the [errors] section in the configuration docs to find them.

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Part 3: Write Your Own Code

At the bottom of challenge.py there's a stub function called score_quests(). Fill it in with 20–50 lines of type-safe code. No Any allowed!

Read the docstring for what to implement, then get creative with the scoring logic!

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Claim Your Swag

Once you're done, show your work to Meta booth staff to claim a reward (while supplies last). They'll want to see:

1. Your pyrefly.toml setup
2. A clean pyrefly check challenge.py with zero errors
3. A quick walk-through of your score_quests() solution

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Side Quest: Teach Your AI Agent

Want your AI coding assistant to use Pyrefly automatically? Set up a rules file so your agent type-checks with Pyrefly out of the box.

Claude Code — add a CLAUDE.md file

# Type Checking

Use pyrefly for type checking Python files:
- Run `pyrefly check <file>` to check for type errors
- Fix all type errors before committing
- Never use `Any` — use proper type annotations

GitHub Copilot — add .github/copilot-instructions.md

Use pyrefly for Python type checking. Run `pyrefly check` on all Python files
before suggesting changes. Ensure code is fully annotated with no use of Any.

Cursor — add a .cursor/rules file

Use pyrefly for Python type checking. Run `pyrefly check` on all Python files.
Ensure code is fully annotated with no use of Any.

This is optional — but it's a great habit to start!

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What is Pyrefly?

Pyrefly is a fast type checker and language server for Python, built in Rust. It's designed to be lightning-fast, easy to configure, and a joy to use.

• GitHub
• Docs

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Happy typing!

~ The Pyrefly Team at Meta ~