gradual-typing-implementer
Skill17 starsChanged 9 months agoApache-2.0View on GitHub
Implements gradual typing for dynamically-typed languages. Use when:
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The file
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3 rules. About 0 are common, 3 are distinctive, and 0 are very specific to this project.
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Distinctive · estimate
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- Common
- Distinctive
- Very specific
- Distinctive: line 61
Start with simple gradual system
- Distinctive: line 62
Use "any" as bottom for gradual
- Distinctive: line 65
Test with mixed static/dynamic code
≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
Gradual Typing Implementer
Implements gradual typing systems that bridge static and dynamic typing.
When to Use
- Adding type checking to dynamic languages
- Supporting migration to static types
- Building hybrid type systems
- Implementing TypeScript-like systems
- Creating typed dialects of Python/Ruby
What This Skill Does
- Defines gradual types - Static + dynamic + ? types
- Implements type checking - Consistent with gradual guarantee
- Handles casts - Runtime type checks
- Manages errors - Type mismatch reporting
Key Concepts
| Concept | Description |
| Gradual guarantee | Adding static types doesn't change behavior |
| Consistent-with | Flexible type matching (★) |
| Unknown type | Explicitly unknown ('?') |
| Type precision | Dynamic < Unknown < Static |
The ★ Relation
| Type A | Type B | A consistent B? |
| int | int | ✓ |
| int | dynamic | ✓ |
| dynamic | int | ✓ |
| int | string | ✗ |
| (int → int) | (dynamic → int) | ✓ |
Tips
- Start with simple gradual system
- Use "any" as bottom for gradual
- Preserve dynamic behavior
- Good error messages are crucial
- Test with mixed static/dynamic code
Related Skills
type-checker-generator- Static type checkingtype-inference-engine- Type inferencerefinement-type-checker- Refinement types
Canonical References
| Reference | Why It Matters |
| Siek & Taha, "Gradual Typing for Functional Languages" (2006) | Original gradual typing |
| Siek et al., "Gradual Typing in Practice" | Practical gradual typing |
| TypeScript Language Specification | Production gradual typing |
| Typed Racket | Gradual typing in practice |
Tradeoffs and Limitations
Design Tradeoffs
| Approach | Pros | Cons |
| Erasure | Simple, fast | Runtime overhead |
| Reified | Type info at runtime | Memory |
| Blame | Clear error responsibility | Complexity |
Limitations
- Runtime overhead for checks
- Cannot fully verify static properties
- Type inference is harder
- Error messages can be confusing
- Performance tuning is complex
Research Tools & Artifacts
Gradual typing in practice:
| Tool | Language | What to Learn |
| TypeScript | JavaScript | Production gradual |
| Typed Racket | Racket | Academic |
| Pyright | Python | Gradual |
Research Frontiers
1. Blame Tracking
- Goal: Error localization
Implementation Pitfalls
| Pitfall | Real Consequence | Solution |
| Runtime overhead | Slow checks | Optimize |
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