#11028: Refactor ConDecl -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 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: -------------------------------------+------------------------------------- The `ConDecl` type in `HsDecls` is an uneasy compromise. For the most part, `HsSyn` directly reflects the syntax written by the programmer; and that gives just the right "pegs" on which to hang Alan's [wiki:ApiAnnotations API annotations]. But `ConDecl` doesn't properly reflect the syntax of Haskell-98 and GADT-style data type declarations. To be concrete, here's a draft new data type {{{ data ConDecl name | ConDeclGADT { con_names :: [Located name] , con_type :: LHsSigType name -- The type after the ‘::’ , con_doc :: Maybe LHsDocString , con_old_rec :: Bool } | ConDeclH98 { con_name :: Located name , con_implict :: HsImplicitBndrs () -- ^ Implicit binders, added by renamer , con_qvars :: Maybe [LHsTyVarBndr name] -- User-written foralls (if any) , con_cxt :: Maybe (LHsContext name) -- ^ User-written context (if any) , con_details :: HsConDeclDetails name -- ^ Arguments , con_doc :: Maybe LHsDocString -- ^ A possible Haddock comment. } deriving (Typeable) }}} Note that * For GADTs, just keep a type. That's what the user writes. (NB: `HsType` can represent records on the LHS of an arrow: `{ x:Int,y:Bool } -> T` * `con_qvars` and `con_cxt` are both `Maybe` because they are both optional (the `forall` and the context of an existential data type) * The `con_old_rec` is a warning thing for GADTs (see current source code) This ticket is just to track the thought and invite feedback. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11028 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler