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To Proof Maintenance & Beyond!

976 papers · page 21 of 49

GADTs Meet Subtyping

Gabriel Scherer, Didier Rémy

While generalized algebraic datatypes (GADTs) are now considered well-understood, adding them to a language with a notion of subtyping comes with a few surprises. What does it mean for a GADT parameter to be covariant? The answer turns out to be quite subtle. It involves fine-gra…