#12978: User guide section on AllowAmbiguousTypes should mention TypeApplications -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: newcomer | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts... #ghc-flag--XAllowAmbiguousTypes With type applications it is tempting to write {{{ class C x a where meth :: a }}} which will fail the ambiguity check as `x` is not used in any methods. One way to get around this is to use `TypeApplications` in order to specify what `x` should be at each usage of `meth`. A small section in the user guide explaining this and linking to the section on `TypeApplications` would be useful. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12978 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler