An abbreviated form of module, consisting only of the module body, is
#13839: GHC warnings do not respect the default module header -------------------------------------+------------------------------------- Reporter: Feuerbach | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- If I compile this program with `-Wall`, I get no warnings: {{{#!hs type T = Int main :: IO () main = return () }}} If I add a module header: {{{#!hs module Main(main) where type T = Int main :: IO () main = return () }}} I now get a warning: {{{ ghcbug2.hs:3:1: warning: [-Wunused-top-binds] Defined but not used: type constructor or class ‘T’ }}} Yet, according to Haskell2010 (section 5.1): permitted. If this is used, the header is assumed to be ‘module Main(main) where’. Therefore, the right behaviour should be to print a warning in the first case as well. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13839 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler