The one tiny caveat is the new feature for deriving Foldable for GADTs, which distinguishes among the two forms above. (I can't find a reference to this change. Can you? It was described at Haskell Implementors' Workshop a few days ago. You, the reader, if you know the reference,
#10828: TH could do a better job of representing GADTs -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Template Haskell | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by simonpj): please add it!) See [wiki:Commentary/Compiler/DeriveFunctor] and #10447. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10828#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler