#14761: Incorrect diagnostic for UNPACK/missing strictness -------------------------------------+------------------------------------- Reporter: dminuoso | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple error/warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: #7210 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): This happens because both strictness annotations (`!`) and `UNPACK` annotations can decorate //any// type, and moreover, they bind more tightly than application. Therefore, this: {{{#!hs {-# UNPACK #-} Maybe Int }}} is shorthand for this: {{{#!hs ({-# UNPACK #-} Maybe) Int }}} You'll notice that you'll get a similar error if you had written `a :: ! Maybe Int`. So the error isn't incorrect—you are in fact putting `{-# UNPACK #-}` in the wrong place, and should have written it as `{-# UNPACK #-} (Maybe Int)`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14761#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler