Type-level interfaces in Haskell & Rust: pragmatic type-level programming

on YouTube ↗38m

" summary

Presents a concrete design for type-level interfaces implemented in Rust and Haskell: existential wrappers + associated-type traits that hide implementation types, macros to emulate type-level strings, and a universal eval/verbs interpreter that maps declarative type-level HTTP DSLs to runtime servers. Demo code targets tiny-http and axum (partial coverage) and shows adding new methods or handlers without rebuilding core code, arguing the approach solves the expression problem and makes many invalid API states unrepresentable at compile time.

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" chapters (10)

1. 0:00Introduction to FP design
2. 2:52Methodologies and goals
3. 6:39Designing type-level eDSLs
4. 10:37Core interface concepts
5. 13:22Implementing model domains
6. 16:18Existential wrappers and types
7. 21:44Evaluation and interpretation
8. 25:23Extensibility patterns
9. 28:40Advanced topics and Q&A
10. 35:25Technical details and conclusion

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