I have no idea what all this means. But it looks plausible that it's
#9112: support for deriving Vector/MVector instances -------------------------------------+------------------------------------ Reporter: jwlato | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by tibbe): Replying to [comment:7 simonpj]: the same issue, and is rightly rejected on the grounds that it could be unsound. We have yet to figure out a way to solve this; see #9123. I can't tell, from the cabal message, whether cabal gave up early or there's in fact no install plan possible. If it's the former then cabal- install-1.20.0.2 (released last weekend) has several solver improvements that might let it find a solution that lets you build. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9112#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler