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Writing .hu Files

.hu (Human) files are plain-text prompt templates. They define instructions for an LLM in natural language, with parameter placeholders for dynamic content.

Syntax

A .hu file is plain text with single-brace parameter placeholders:

You are an expert code reviewer.

Review the following code for correctness, security, and performance issues.

Code to review:
{code}

Focus areas:
{focus_areas}

Rules

  • Plain text only — no markdown (no **bold**, # headers, `backticks`, or HTML)
  • Single braces for parameters: {param_name} (double braces {{text}} become literal text with {text} value when sent to the LLM)
  • No output format descriptions — Lamia enforces output schemas and .hu files should be return type agnostic to be reusable.
  • Keep them concise — shorter prompts perform better

Calling .hu Files

From a .lm file:

result = review_code(code=source_text, focus_areas="security") -> JSON[ReviewResult]

This calls review_code.hu, substitutes the parameters, sends it to the LLM, and parses the response as ReviewResult.

IDE Features for .hu Files

  • Syntax highlighting — parameters {name} are highlighted distinctly
  • Go to definition — Ctrl+Click / Cmd+Click on a .hu filename in .lm code jumps to the file
  • Hover info — hover over a .hu call to see the template contents and parameters
  • Completions — parameter names suggested when calling .hu files

To quickly navigate between .lm and .hu files:

  1. In a .lm file, Ctrl+Click / Cmd+Click on any .hu call to jump to it
  2. Use Ctrl+Shift+O / Cmd+Shift+O for document symbols — lists all functions and .hu calls
  3. Use Ctrl+P / Cmd+P and type .hu to find prompt files by name

For the full .hu syntax reference, see the Lamia Language Docs — .hu Syntax.