Vibe Engineering Effect Apps — Michael Arnaldi, Effectful

What if the best way to get coding agents to use a library well is not better prompts, but giving them the library's actual code? In this workshop, Michael Arnaldi walks through a practical approach to building with Effect and LLMs by cloning the Effect repo into the project, extracting patterns directly from the source, and using those patterns to guide agent behavior. Starting from an empty repository, the session shows how to set up an Effect-based app with tests, strict TypeScript diagnostics, agent instructions, and a simple HTTP API, while also exploring the broader problem of how to make agents effective in unfamiliar codebases. If you're building with coding agents and care about reliability, structure, and real-world Effect workflows, this is a useful hands-on framing. Speaker info: - https://x.com/MichaelArnaldi - https://www.linkedin.com/in/michael-arnaldi-52858114a/