Pencils Down, Notation Up
3 hours ago
- The keynote at Rails World 2026 promoted embracing LLMs and optimism, claiming there is only one choice to lean into the future.
- The author disagrees, arguing there are more choices and that Rails and agentic futures can coexist, with DHH's drill bit analogy highlighting the need for a source of truth.
- A thought experiment comparing Campfire in Rails (60k tokens) vs compiled C (4M tokens) shows Rails is easier for agents to edit due to context size, single declarations, intent preservation, deterministic output, and model familiarity.
- Maintaining a prompt as source of truth essentially creates a new DSL, while Rails already serves as a refined, conventional specification.
- Performance gains (e.g., 85-140x throughput via compilation) can be achieved without abandoning Rails at the top, as most cost comes from runtime interpretation of declarations.
- The conclusion advocates for 'pencils down, notation up': using Rails as the compact, precise specification compiled to any target.