This talk was given at ViennaJS July 2025 by David Pichenmeister.
Prompt engineering is more and more becoming a valuable developer skill. But most developers just write prompts as unstructured blobs of text, often directly in the code. That works fine for quick tests, but can be a pain for real-world projects. The FML (Freeform Markup Language) Node SDK provides a better way to structure, reuse, and maintain prompts in Javascript, just like we do with code. Inspired by XML, FML introduces an easy to use tag-style syntax without the strict structure of XML.
In this talk we'll go into:
- What tag-style prompts are and why they’re important for prompt engineering
- How FML helps you organize prompts like source code
- How to build prompts using <include>, variables, and a clean structure