diff options
| author | Manuel M T Chakravarty <chak@cse.unsw.edu.au> | 2006-12-29 20:17:51 +0000 |
|---|---|---|
| committer | Manuel M T Chakravarty <chak@cse.unsw.edu.au> | 2006-12-29 20:17:51 +0000 |
| commit | c8732b3c99e93c36ad28e23d2b901b794e89542a (patch) | |
| tree | 2a7aa06227c0b170d0551f304d048c1c4aa0d29c /compiler | |
| parent | 0aa1d46a1e5c19553c410dc6ff65b29594a2499f (diff) | |
| download | haskell-c8732b3c99e93c36ad28e23d2b901b794e89542a.tar.gz | |
EqPred pretty prints as ~ and equalities without brackets
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/parser/Parser.y.pp | 9 | ||||
| -rw-r--r-- | compiler/types/TypeRep.lhs | 8 |
2 files changed, 11 insertions, 6 deletions
diff --git a/compiler/parser/Parser.y.pp b/compiler/parser/Parser.y.pp index 009eddca62..f72c8b9d83 100644 --- a/compiler/parser/Parser.y.pp +++ b/compiler/parser/Parser.y.pp @@ -971,8 +971,13 @@ ctype :: { LHsType RdrName } -- errors in ctype. The basic problem is that -- (Eq a, Ord a) -- looks so much like a tuple type. We can't tell until we find the => +-- +-- We have the t1 ~ t2 form here and in gentype, to permit an individual +-- equational constraint without parenthesis. context :: { LHsContext RdrName } - : btype {% checkContext $1 } + : btype '~' btype {% checkContext + (LL $ HsPredTy (HsEqualP $1 $3)) } + | btype {% checkContext $1 } type :: { LHsType RdrName } : ipvar '::' gentype { LL (HsPredTy (HsIParam (unLoc $1) $3)) } @@ -983,7 +988,7 @@ gentype :: { LHsType RdrName } | btype qtyconop gentype { LL $ HsOpTy $1 $2 $3 } | btype tyvarop gentype { LL $ HsOpTy $1 $2 $3 } | btype '->' ctype { LL $ HsFunTy $1 $3 } - | btype '~' gentype { LL $ HsPredTy (HsEqualP $1 $3) } + | btype '~' btype { LL $ HsPredTy (HsEqualP $1 $3) } btype :: { LHsType RdrName } : btype atype { LL $ HsAppTy $1 $2 } diff --git a/compiler/types/TypeRep.lhs b/compiler/types/TypeRep.lhs index 111d194be4..6a9c609eea 100644 --- a/compiler/types/TypeRep.lhs +++ b/compiler/types/TypeRep.lhs @@ -232,7 +232,7 @@ Predicates are represented inside GHC by PredType: data PredType = ClassP Class [Type] -- Class predicate | IParam (IPName Name) Type -- Implicit parameter - | EqPred Type Type -- Equality predicate (ty1 :=: ty2) + | EqPred Type Type -- Equality predicate (ty1 ~ ty2) type ThetaType = [PredType] \end{code} @@ -251,7 +251,7 @@ represented by evidence (a dictionary, for example, of type (predRepTy p). Note [Equality predicates] ~~~~~~~~~~~~~~~~~~~~~~~~~~ - forall a b. (a :=: S b) => a -> b + forall a b. (a ~ S b) => a -> b could be represented by ForAllTy a (ForAllTy b (FunTy (PredTy (EqPred a (S b))) ...)) OR @@ -395,7 +395,7 @@ isLiftedTypeKind (TyConApp tc []) = isLiftedTypeKindCon tc isLiftedTypeKind other = False isCoercionKind :: Kind -> Bool --- All coercions are of form (ty1 :=: ty2) +-- All coercions are of form (ty1 ~ ty2) -- This function is here rather than in Coercion, -- because it's used in a knot-tied way to enforce invariants in Var isCoercionKind (NoteTy _ k) = isCoercionKind k @@ -436,7 +436,7 @@ pprParendType ty = ppr_type TyConPrec ty pprPred :: PredType -> SDoc pprPred (ClassP cls tys) = pprClassPred cls tys pprPred (IParam ip ty) = ppr ip <> dcolon <> pprType ty -pprPred (EqPred ty1 ty2) = sep [ppr ty1, nest 2 (ptext SLIT(":=:")), ppr ty2] +pprPred (EqPred ty1 ty2) = sep [ppr ty1, nest 2 (ptext SLIT("~")), ppr ty2] pprClassPred :: Class -> [Type] -> SDoc pprClassPred clas tys = parenSymOcc (getOccName clas) (ppr clas) |