#11440: GHC.Prim does not export Constraint -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.0.1-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This code from the `effect-monad` library worked in ghc-7.10, but fails with ghc-8.0.1-rc1: {{{ {-# LANGUAGE TypeFamilies, ConstraintKinds, PolyKinds #-} module Control.Effect.Cond where import GHC.Prim class Cond (m :: k -> * -> *) where type AltInv m (s :: k) (t :: k) :: Constraint }}} It seems one now needs to import `Constraint` from `GHC.Exts`. This should be mentioned in the migration guide (https://ghc.haskell.org/trac/ghc/wiki/Migration/8.0), together with any other breaking changes there might be from the kind equalities patch (6746549772c5cc0ac66c0fce562f297f4d4b80a2). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11440 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler