diff options
Diffstat (limited to 'compiler/parser')
| -rw-r--r-- | compiler/parser/Parser.y.pp | 3 | ||||
| -rw-r--r-- | compiler/parser/RdrHsSyn.lhs | 40 |
2 files changed, 25 insertions, 18 deletions
diff --git a/compiler/parser/Parser.y.pp b/compiler/parser/Parser.y.pp index f349f30770..d35d4e2c08 100644 --- a/compiler/parser/Parser.y.pp +++ b/compiler/parser/Parser.y.pp @@ -981,7 +981,8 @@ gentype :: { LHsType RdrName } : btype { $1 } | btype qtyconop gentype { LL $ HsOpTy $1 $2 $3 } | btype tyvarop gentype { LL $ HsOpTy $1 $2 $3 } - | btype '->' ctype { LL $ HsFunTy $1 $3 } + | btype '->' ctype { LL $ HsFunTy $1 $3 } + | btype '~' gentype { LL $ HsPredTy (HsEqualP $1 $3) } btype :: { LHsType RdrName } : btype atype { LL $ HsAppTy $1 $2 } diff --git a/compiler/parser/RdrHsSyn.lhs b/compiler/parser/RdrHsSyn.lhs index 03d4c413a1..200ea576a0 100644 --- a/compiler/parser/RdrHsSyn.lhs +++ b/compiler/parser/RdrHsSyn.lhs @@ -97,8 +97,9 @@ extractHsRhoRdrTyVars ctxt ty extract_lctxt ctxt acc = foldr (extract_pred . unLoc) acc (unLoc ctxt) -extract_pred (HsClassP cls tys) acc = foldr extract_lty acc tys -extract_pred (HsIParam n ty) acc = extract_lty ty acc +extract_pred (HsClassP cls tys) acc = foldr extract_lty acc tys +extract_pred (HsEqualP ty1 ty2) acc = extract_lty ty1 (extract_lty ty2 acc) +extract_pred (HsIParam n ty ) acc = extract_lty ty acc extract_lty (L loc ty) acc = case ty of @@ -406,6 +407,15 @@ checkInstType (L l t) ty -> do dict_ty <- checkDictTy (L l ty) return (L l (HsForAllTy Implicit [] (noLoc []) dict_ty)) +checkDictTy :: LHsType RdrName -> P (LHsType RdrName) +checkDictTy (L spn ty) = check ty [] + where + check (HsTyVar t) args | not (isRdrTyVar t) + = return (L spn (HsPredTy (HsClassP t args))) + check (HsAppTy l r) args = check (unLoc l) (r:args) + check (HsParTy t) args = check (unLoc t) args + check _ _ = parseError spn "Malformed instance header" + -- Check whether the given list of type parameters are all type variables -- (possibly with a kind signature). If the second argument is `False', -- only type variables are allowed and we raise an error on encountering a @@ -477,10 +487,12 @@ checkTyClHdr (L l cxt) ty go l other acc = parseError l "Malformed head of type or class declaration" - -- The predicates in a type or class decl must all - -- be HsClassPs. They need not all be type variables, - -- even in Haskell 98. E.g. class (Monad m, Monad (t m)) => MonadT t m - chk_pred (L l (HsClassP _ args)) = return () + -- The predicates in a type or class decl must be class predicates or + -- equational constraints. They need not all have variable-only + -- arguments, even in Haskell 98. + -- E.g. class (Monad m, Monad (t m)) => MonadT t m + chk_pred (L l (HsClassP _ _)) = return () + chk_pred (L l (HsEqualP _ _)) = return () chk_pred (L l _) = parseError l "Malformed context in type or class declaration" @@ -571,22 +583,16 @@ checkPred (L spn ty) where checkl (L l ty) args = check l ty args + check _loc (HsPredTy pred@(HsEqualP _ _)) + args | null args + = return $ L spn pred check _loc (HsTyVar t) args | not (isRdrTyVar t) = return (L spn (HsClassP t args)) check _loc (HsAppTy l r) args = checkl l (r:args) check _loc (HsOpTy l (L loc tc) r) args = check loc (HsTyVar tc) (l:r:args) check _loc (HsParTy t) args = checkl t args - check loc _ _ = parseError loc "malformed class assertion" - -checkDictTy :: LHsType RdrName -> P (LHsType RdrName) -checkDictTy (L spn ty) = check ty [] - where - check (HsTyVar t) args | not (isRdrTyVar t) - = return (L spn (HsPredTy (HsClassP t args))) - check (HsAppTy l r) args = check (unLoc l) (r:args) - check (HsParTy t) args = check (unLoc t) args - check _ _ = parseError spn "Malformed context in instance header" - + check loc _ _ = parseError loc + "malformed class assertion" --------------------------------------------------------------------------- -- Checking stand-alone deriving declarations |