#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 simonpj): I can't reproduce this because I fall at an early fence: {{{ bash$ cabal install hackage-server Resolving dependencies... cabal: Could not resolve dependencies: trying: hackage-server-0.4 (user goal) trying: base-4.7.0.0/installed-018... (dependency of hackage-server-0.4) next goal: process (dependency of hackage-server-0.4) rejecting: process-1.2.0.0/installed-eaf... (conflict: process => unix==2.7.0.1/installed-23f..., hackage-server => unix<2.7) trying: process-1.2.0.0 next goal: Cabal (dependency of hackage-server-0.4) rejecting: Cabal-1.18.1.3/installed-9a9..., 1.20.0.0, 1.18.1.3, 1.18.1.2, 1.18.1.1, 1.18.1, 1.18.0 (conflict: hackage-server => Cabal>=1.16 && <1.17) trying: Cabal-1.16.0.3 rejecting: Cabal-1.16.0.3:+base3 (conflict: process==1.2.0.0, Cabal-1.16.0.3:base3 => process>=1 && <1.2) rejecting: Cabal-1.16.0.3:-base3 (conflict: base==4.7.0.0/installed-018..., Cabal-1.16.0.3:base3 => base<3) Backjump limit reached (change with --max-backjumps). bash$ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.8.2 }}} I have no idea what all this means. But it looks plausible that it's 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 do not know whether this is a show-stopper any particular packages, and if so which. Nor do I know if there is a reasonable way to work around it. Perhaps others will know more than I do. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9112#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler