http_server_demo_yo

A simple HTTP/1.1 server written in the Yo programming language.

Features

• Async I/O — Uses io.await with IO algebraic effect for non-blocking TCP networking
• Algebraic effects — Exception effect for structured error handling (per-connection error isolation)
• HTTP parsing — Hand-written HTTP/1.1 request parser (method, path, headers, body)
• Routing — Simple path-based router with multiple response types

Routes

Path	Description
/	HTML welcome page with links to other routes
/hello	Plain text Hello, World!
/json	JSON response with language info
/echo	Echo back request method, path, and headers as HTML
*	404 Not Found

Build & Run

yo build
./yo-out/bin/http_server_demo_yo

Then visit http://localhost:8080 or test with curl:

curl http://localhost:8080/
curl http://localhost:8080/hello
curl http://localhost:8080/json
curl -H "X-Custom: test" http://localhost:8080/echo

Project Structure

http_server_demo_yo/
├── build.yo          # Build configuration
├── src/
│   └── main.yo       # HTTP server implementation (~250 lines)
└── README.md

Yo Language Features Demonstrated

• async/await via the IO effect and io.await
• Algebraic effects with given/Exception/escape for error handling
• TCP server with TcpListener.bind, listener.accept, stream.read/write
• String processing with split, index_of, substring, trim
• Pattern matching with match and cond
• while runtime(true) for infinite accept loops
• Template strings for HTML/JSON response building