There is now some potential ambiguity in import and export lists; for example if you write import M( (+) ) do you mean the function (+) or the type constructor (+)? The default is the former, but with -XExplicitNamespaces (which is implied by -XExplicitTypeOperators) GHC allows you to specify the latter by preceding it with the keyword type,

#10175: User's Guide 7.4.4 ExplicitTypeOperators typo -------------------------------------+------------------------------------- Reporter: Shou | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.8.4 Documentation | Operating System: Unknown/Multiple Keywords: typo | Type of failure: None/Unknown extension | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- thus: [...] GHC lists no extension `-XExplicitTypeOperators`, so it is assumed to be a mistake intended to be `-XTypeOperators`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10175 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler