Magnolia: Generic Derivation 2.0
summary
Magnolia is a ~400-line Apache-2 macro that generates typeclass instances for case classes, sealed traits, case objects, value classes and tuples, with special support for recursive ADTs and implicit prioritization. It deduplicates generated code and caches implicit searches so compilation can be much faster — one example shows 2 seconds vs ~50 seconds for a large ADT; worst-case measured speedups reach 4x and a microbenchmark gave 52x when creating a million instances. It also produces better error traces when derivation fails.
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chapters (7)
- 0:00Introduction
- 0:49What is generic derivation
- 5:48What is Magnolia
- 9:51Type class
- 14:57Contravariant types
- 19:01Compiler performance
- 21:20Lifted case parameters
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