A few weeks ago, Anthropic introduced “subagents” to Claude Code (their command-line AI coding tool) - basically specialized AI assistants for specific purposes. I thought it would be interesting to create one specifically tuned for Elm development.
I’ve put together what I’m calling an “Elm Expert” subagent running on Claude Sonnet 4. It’s configured to understand Elm syntax, types, and core libraries, along with The Elm Architecture, common patterns, the package ecosystem, and functional programming as it applies to Elm.
I’ve only been using it briefly, so this is definitely experimental territory. So far it’s been helpful for Claude Code getting unstuck on less common syntax, suggesting idiomatic Elm patterns, and debugging compiler errors, though it’s not always perfect. The usual AI caveats apply - it makes mistakes, especially with recent ecosystem changes.
I figured this might be useful for others, especially those newer to Elm. Here’s the subagent prompt: https://gist.github.com/hasko/08bc06557f461f4df2318b4fd1e3d739
Note: I am in no way affiliated with Anthropic, just a user here.