Question 1

How do I parse an HTTP request with fast-http in Common Lisp?

Accepted Answer

Create an http-request structure, use make-parser with callbacks for headers and body, and feed byte data to the parser closure. The README provides an example with body-callback and finish-callback for handling incremental parsing.

Question 2

fast-http vs http-parse for Lisp projects?

Accepted Answer

fast-http is faster and uses structure classes for performance, but http-parse offers standard classes and :store-body for convenience. Choose fast-http for speed and low-level control, or http-parse for easier high-level usage.

Question 3

Does fast-http support WebSocket upgrades?

Accepted Answer

Yes, it can detect WebSocket upgrades via the http-upgrade-p method, but you'll need to handle the upgrade logic externally since it's only a parser, not a full server implementation.

Question 4

How to handle multipart form data with fast-http?

Accepted Answer

Use make-multipart-parser with the content-type and a callback function that receives field names, headers, meta data, and body bytes. It's a separate parser, so integrate it with the main body-callback as needed.

Question 5

Is fast-http suitable for building HTTP servers?

Accepted Answer

Yes, but it's only a parser; you'll need to pair it with a socket library and manually handle request/response logic. It's best for low-level protocol parsing rather than out-of-the-box server solutions.

Question 6

What are the performance benchmarks for fast-http?

Accepted Answer

According to the README, it parses 100,000 HTTP request headers in 0.086 seconds, outperforming a C equivalent. However, real-world performance depends on callback implementation and data size.

Question 7

How to handle errors in fast-http parsing?

Accepted Answer

Catch fast-http-error conditions in your code, as the parser raises errors aggressively. Implement error handling routines to manage malformed inputs without disrupting application flow.

fast-http

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