LIFTING DATA STRUCTURES TO THE TYPE-LEVEL

on YouTube ↗32m

" summary

Shows how value-level List/Set/Map lift to type-level equivalents (HList, HSet, HMap) and proves it’s practical: uses implicit-based type classes for contains on HLists, uses intersection types plus a contravariant wrapper to model HSet with deduplication, wraps elements in an invariant HLN to avoid unwanted subtyping, and uses Scala unification and singleton types to implement HMap and DAG references. Compiler prevents invalid forward/cyclic references; implicit search can be slow but the constructions compile and work.

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" chapters (6)

1. 0:00Start
2. 2:38Recursive Function
3. 9:40Intersection Types
4. 16:39Type Alias
5. 25:22Directed Acyclic Graphs
6. 28:06Compile Error

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