diff options
Diffstat (limited to 'compiler/Language/Haskell/Syntax/Decls.hs')
| -rw-r--r-- | compiler/Language/Haskell/Syntax/Decls.hs | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/compiler/Language/Haskell/Syntax/Decls.hs b/compiler/Language/Haskell/Syntax/Decls.hs index 0af2cfbf94..52475a9dfe 100644 --- a/compiler/Language/Haskell/Syntax/Decls.hs +++ b/compiler/Language/Haskell/Syntax/Decls.hs @@ -45,7 +45,7 @@ module Language.Haskell.Syntax.Decls ( FamilyDecl(..), LFamilyDecl, -- ** Instance declarations - InstDecl(..), LInstDecl, FamilyInfo(..), + InstDecl(..), LInstDecl, FamilyInfo(..), familyInfoTyConFlavour, TyFamInstDecl(..), LTyFamInstDecl, TyFamDefltDecl, LTyFamDefltDecl, DataFamInstDecl(..), LDataFamInstDecl, @@ -99,12 +99,14 @@ import Language.Haskell.Syntax.Extension import Language.Haskell.Syntax.Type import Language.Haskell.Syntax.Basic (Role) -import GHC.Types.Basic (TopLevelFlag, OverlapMode, RuleName, Activation) +import GHC.Types.Basic (TopLevelFlag, OverlapMode, RuleName, Activation + ,TyConFlavour(..), TypeOrData(..)) import GHC.Types.ForeignCall (CType, CCallConv, Safety, Header, CLabelString, CCallTarget, CExportSpec) import GHC.Types.Fixity (LexicalFixity) import GHC.Core.Type (Specificity) import GHC.Unit.Module.Warnings (WarningTxt) +import GHC.Utils.Panic.Plain ( assert ) import GHC.Hs.Doc (LHsDoc) -- ROMES:TODO Discuss in #21592 whether this is parsed AST or base AST @@ -863,6 +865,28 @@ data FamilyInfo pass -- said "type family Foo x where .." | ClosedTypeFamily (Maybe [LTyFamInstEqn pass]) +familyInfoTyConFlavour + :: Maybe tc -- ^ Just cls <=> this is an associated family of class cls + -> FamilyInfo pass + -> TyConFlavour tc +familyInfoTyConFlavour mb_parent_tycon info = + case info of + DataFamily -> OpenFamilyFlavour IAmData mb_parent_tycon + OpenTypeFamily -> OpenFamilyFlavour IAmType mb_parent_tycon + ClosedTypeFamily _ -> assert (isNothing mb_parent_tycon) + -- See Note [Closed type family mb_parent_tycon] + ClosedTypeFamilyFlavour + +{- Note [Closed type family mb_parent_tycon] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +There's no way to write a closed type family inside a class declaration: + + class C a where + type family F a where -- error: parse error on input ‘where’ + +In fact, it is not clear what the meaning of such a declaration would be. +Therefore, 'mb_parent_tycon' of any closed type family has to be Nothing. +-} {- ********************************************************************* * * |