Type Clash: When Structural and Nominal Systems Collide

on YouTube ↗43m

" summary

Compares concrete examples: a TypeScript query DSL that computes result types from select/where expressions and rejects invalid field operations at compile time, and a Kotlin compile-time FSM that encodes order states and two-step approvals so illegal transitions never compile; both demos compile and behave as claimed. Claims that structural typing wins for type-level computation and dynamic type construction (API integration, ad-hoc composition), while nominal typing wins for identity, semantic safety, and refactor-safe invariants enforced by the compiler.

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" chapters (8)

1. 0:00Structural vs nominal types
2. 4:37Structural type systems
3. 9:39Nominal type systems
4. 15:00Trade-offs between systems
5. 16:05Structural typing in queries
6. 23:54Nominal typing for FSMs
7. 32:11Key takeaways
8. 35:21Q&A

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