#9792: map/coerce rule never seems to fire -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: ekmett Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Core | Version: 7.9 Libraries | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: Runtime | Related Tickets: performance bug | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by nomeata): I was confused. I thought for a moment that the type of `$dCoercible_arz`, i.e. `Coercible` is the same as the `Coercion` thingy, and the latter can be undefined. But they are not, `Coercion` adds another box around `Coercible`, I guess we avoid `Coercion` to be undefined. But `Coercible` is a lifted type, so I’m not sure that we can guarantee that there is no way to produce a bottom here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9792#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler