#1830: Automatic derivation of Lift -------------------------------------+------------------------------------- Reporter: guest | Owner: | RyanGlScott Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Template Haskell | Version: 6.8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1168 -------------------------------------+------------------------------------- Comment (by rwbarton):

What should we do if someone attempts to derive `Lift` on a datatype with no constructors?

Since `lift` then has type `Void -> Q Exp`, I would be inclined to define it as `absurd`, i.e., an empty case. I don't see the point of turning it into a runtime error when `lift (error "foo")` is a splice-time error for an inhabited type. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/1830#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler