Type Theory
Expert skill in type theory foundations for implementing type systems including inference, checking, and subtyping
npx skills add a5c-ai/babysitter --skill type-theory --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Type Theory Skill ## Overview Expert skill in type theory foundations for implementing type systems including inference, checking, and subtyping. ## Capabilities - Implement Hindley-Milner type inference with Algorithm W - Implement constraint-based type inference with unification - Design and implement bidirectional type checking - Implement structural and nominal subtyping - Handle variance (covariant, contravariant, invariant) - Implement row polymorphism and record types - Design flow-sensitive type narrowing - Implement type error message generation ## Target Processes - type-system-implementation.js - semantic-analysis.js - generics-polymorphism.js - effect-system-design.js ## Dependencies Academic type theory literature (TAPL, ATTAPL) ## Usage Guidelines 1. **Algorithm Selection**: Choose between HM inference and bidirectional checking based on language features 2. **Constraint Generation**: Separate constraint generation from solving for cleaner implementation 3. **Error Localization**: Track constraint origins for accurate error location 4. **Variance**: Document variance rules explicitly for all generic positions 5. **Gradual Typing**: Consider gradual typing for mixed
- Overview
- Capabilities
- Target Processes
- Dependencies
- Usage Guidelines
- Output Schema
What does the Type Theory skill do?
Expert skill in type theory foundations for implementing type systems including inference, checking, and subtyping
How do I install it?
Run `npx skills add a5c-ai/babysitter --skill type-theory --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From a5c-ai/babysitter, a repository with 1,642 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.