Deriving as a library (Lightning Talk)
summary
Proposes removing the deriving keyword from GHC and implementing deriving as a library using first-class instances and a simple dict primitive that exposes class dictionaries as values. Provides a proof-of-concept library at gitlab.com/lysxia/ad-lib implemented with Template Haskell, demonstrating deriving-via, generic deriving, and a generic ISO-functor derivation that covers many classes. Prototype works for most Eq-like and Functor-like cases but fails for Show/Read and does not handle type families; type-family support is explicitly excluded for now.
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chapters (10)
- 0:00Deriving as a library
- 0:22GHC’s deriving problems
- 1:47Move deriving out of GHC
- 2:30First-class type class instances
- 4:22Deriving values via FP
- 5:48Generic deriving without extensions
- 7:37Advanced deriving with isomorphisms
- 9:46Limitations and future
- 10:09Conclusion and overview
- 10:53Q&A on implementation
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