Cookbook

The Cookbook combines Khora language features and shipped standard-library APIs into complete application patterns. Each recipe includes the imports, types, functions, and boundary wiring needed to understand the example as a whole instead of showing an isolated call with important pieces omitted.

Start with the recipe closest to the problem you are solving:

• Build an HTTP service — route requests with Router, Request, Response, and SharedFn.
• Build a typed JSON API — parse JSON, decode typed request bodies, derive encoders/decoders, and return JSON responses.
• Run a database transaction — use the portable Db capability and transaction so failure and cancellation cannot leak an open transaction.
• Take work off a queue safely — register a job with a region before the first ! after it, so a cancellation cannot drop work nobody knows the fiber was holding.
• Bound concurrent work — use Fiber, Nursery, and bounded_nursery to turn a concurrency limit into backpressure.
• Make resource cleanup cancellation-safe — pair scoped and acquire so cleanup runs on return, failure, and cancellation.
• Decode untrusted input — describe a value’s shape once with std::schema, decode it from anywhere, and report every bad field at once.
• Load application configuration — read settings with std::config, report every bad key at once, and keep secrets out of the logs with Redacted.
• Retry a flaky call — pick a Schedule, drive it with retry_while, and test the whole thing in under a millisecond.
• Test code that uses capabilities — supply deterministic handlers without global mutation or test-only branches in application code.
• Trace an operation — implement a Tracer, wrap work with around, and keep span lifetime structured.
• Log, and correlate it with traces — emit one JSON object per line with std::log, and carry the trace and span identifiers onto every line inside a span.

How to read the examples

The examples use current Khora syntax and the public APIs shipped in std. They favor small complete modules over framework-style pseudocode. When a recipe depends on a provider outside std—for example a concrete PostgreSQL connection—it says so at the construction boundary instead of inventing a driver API.

For exact declarations after you understand the pattern, use the Standard Library API reference. For the language rules underneath the pattern, use the Language Reference.