Deriving pleasure
summary
Generates a claim: Magnolia is a compact macro (~300 lines) that produces generic type-class derivations without shapeless, with concrete mechanics — it detects recursion cycles, aborts nested invocations, inserts placeholders and post-processes the generated AST to resolve indirect implicit cycles. It handles recursive and even generic ADTs, emits debuggable derivation traces pointing to the first missing implicit, and currently matches shapeless on speed while promising smaller generated trees after planned deduplication. Useful when automatic, type-safe derivation and clearer error locations matter.
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