%
+% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1998
%
\section[TypeRep]{Type - friends' interface}
\begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module TypeRep (
TyThing(..),
Type(..), TyNote(..), -- Representation visible
funTyCon,
-- Pretty-printing
- pprType, pprParendType, pprTyThingCategory,
- pprPred, pprTheta, pprThetaArrow, pprClassPred,
+ pprType, pprParendType, pprTypeApp,
+ pprTyThing, pprTyThingCategory,
+ pprPred, pprTheta, pprForAll, pprThetaArrow, pprClassPred,
-- Kinds
liftedTypeKind, unliftedTypeKind, openTypeKind,
argTypeKind, ubxTupleKind,
isLiftedTypeKindCon, isLiftedTypeKind,
- mkArrowKind, mkArrowKinds,
+ mkArrowKind, mkArrowKinds, isCoercionKind,
-- Kind constructors...
liftedTypeKindTyCon, openTypeKindTyCon, unliftedTypeKindTyCon,
isTySuperKind, isCoSuperKind,
tySuperKindTyCon, coSuperKindTyCon,
- isCoercionKindTyCon,
-
pprKind, pprParendKind
) where
#include "HsVersions.h"
import {-# SOURCE #-} DataCon( DataCon, dataConName )
-import Monad ( guard )
--- friends:
-import Var ( Var, Id, TyVar, tyVarKind )
-import VarSet ( TyVarSet )
-import Name ( Name, NamedThing(..), BuiltInSyntax(..), mkWiredInName )
-import OccName ( mkOccNameFS, tcName, parenSymOcc )
-import BasicTypes ( IPName, tupleParens )
-import TyCon ( TyCon, mkFunTyCon, tyConArity, tupleTyConBoxity, isTupleTyCon, isRecursiveTyCon, isNewTyCon, mkVoidPrimTyCon, mkSuperKindTyCon, isSuperKindTyCon, mkCoercionTyCon )
-import Class ( Class )
+-- friends:
+import Var
+import VarSet
+import Name
+import OccName
+import BasicTypes
+import TyCon
+import Class
-- others
-import PrelNames ( gHC_PRIM, funTyConKey, tySuperKindTyConKey,
- coSuperKindTyConKey, liftedTypeKindTyConKey,
- openTypeKindTyConKey, unliftedTypeKindTyConKey,
- ubxTupleKindTyConKey, argTypeKindTyConKey, listTyConKey,
- parrTyConKey, hasKey, eqCoercionKindTyConKey )
+import PrelNames
import Outputable
\end{code}
type SuperKind = Type -- Invariant: a super kind is always
-- TyConApp SuperKindTyCon ...
-type Coercion = Type
-
-type CoercionKind = Kind
-
data TyNote = FTVNote TyVarSet -- The free type variables of the noted expression
\end{code}
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}
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
| ATyCon TyCon
| AClass Class
-instance Outputable TyThing where
- ppr thing = pprTyThingCategory thing <+> quotes (ppr (getName thing))
+instance Outputable TyThing where
+ ppr = pprTyThing
+
+pprTyThing :: TyThing -> SDoc
+pprTyThing thing = pprTyThingCategory thing <+> quotes (ppr (getName thing))
pprTyThingCategory :: TyThing -> SDoc
pprTyThingCategory (ATyCon _) = ptext SLIT("Type constructor")
unliftedTypeKindTyCon = mkKindTyCon unliftedTypeKindTyConName
ubxTupleKindTyCon = mkKindTyCon ubxTupleKindTyConName
argTypeKindTyCon = mkKindTyCon argTypeKindTyConName
-eqCoercionKindTyCon =
- mkCoercionTyCon eqCoercionKindTyConName 2 (\ _ -> coSuperKind)
mkKindTyCon :: Name -> TyCon
mkKindTyCon name = mkVoidPrimTyCon name tySuperKind 0
liftedTypeKindTyConName = mkPrimTyConName FSLIT("*") liftedTypeKindTyConKey liftedTypeKindTyCon
openTypeKindTyConName = mkPrimTyConName FSLIT("?") openTypeKindTyConKey openTypeKindTyCon
unliftedTypeKindTyConName = mkPrimTyConName FSLIT("#") unliftedTypeKindTyConKey unliftedTypeKindTyCon
-ubxTupleKindTyConName = mkPrimTyConName FSLIT("(##)") ubxTupleKindTyConKey ubxTupleKindTyCon
+ubxTupleKindTyConName = mkPrimTyConName FSLIT("(#)") ubxTupleKindTyConKey ubxTupleKindTyCon
argTypeKindTyConName = mkPrimTyConName FSLIT("??") argTypeKindTyConKey argTypeKindTyCon
funTyConName = mkPrimTyConName FSLIT("(->)") funTyConKey funTyCon
-eqCoercionKindTyConName = mkWiredInName gHC_PRIM (mkOccNameFS tcName (FSLIT(":=:")))
- eqCoercionKindTyConKey Nothing (ATyCon eqCoercionKindTyCon)
- BuiltInSyntax
-
mkPrimTyConName occ key tycon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ)
key
- Nothing -- No parent object
(ATyCon tycon)
BuiltInSyntax
-- All of the super kinds and kinds are defined in Prim and use BuiltInSyntax,
isTySuperKind (TyConApp kc []) = kc `hasKey` tySuperKindTyConKey
isTySuperKind other = False
+isCoSuperKind :: SuperKind -> Bool
isCoSuperKind (NoteTy _ ty) = isCoSuperKind ty
isCoSuperKind (TyConApp kc []) = kc `hasKey` coSuperKindTyConKey
isCoSuperKind other = False
-isCoercionKindTyCon kc = kc `hasKey` eqCoercionKindTyConKey
-
-
-------------------
--- lastly we need a few functions on Kinds
+-- Lastly we need a few functions on Kinds
isLiftedTypeKindCon tc = tc `hasKey` liftedTypeKindTyConKey
+isLiftedTypeKind :: Kind -> Bool
isLiftedTypeKind (TyConApp tc []) = isLiftedTypeKindCon tc
isLiftedTypeKind other = False
-
+isCoercionKind :: Kind -> Bool
+-- 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
+isCoercionKind (PredTy (EqPred {})) = True
+isCoercionKind other = False
\end{code}
pprType ty = ppr_type TopPrec ty
pprParendType ty = ppr_type TyConPrec ty
+pprTypeApp :: NamedThing a => a -> SDoc -> [Type] -> SDoc
+-- The first arg is the tycon; it's used to arrange printing infix
+-- if it looks like an operator
+-- Second arg is the pretty-printed tycon
+pprTypeApp tc pp_tc tys = ppr_type_app TopPrec (getName tc) pp_tc tys
+
------------------
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)
- <+> sep (map pprParendType tys)
+pprClassPred clas tys = ppr_type_app TopPrec (getName clas) (ppr clas) tys
pprTheta :: ThetaType -> SDoc
pprTheta theta = parens (sep (punctuate comma (map pprPred theta)))
ppr_type :: Prec -> Type -> SDoc
ppr_type p (TyVarTy tv) = ppr tv
-ppr_type p (PredTy pred) = braces (ppr pred)
+ppr_type p (PredTy pred) = ifPprDebug (ptext SLIT("<pred>")) <> (ppr pred)
ppr_type p (NoteTy other ty2) = ppr_type p ty2
ppr_type p (TyConApp tc tys) = ppr_tc_app p tc tys
ppr_forall_type :: Prec -> Type -> SDoc
ppr_forall_type p ty
= maybeParen p FunPrec $
- sep [pprForAll tvs, pprThetaArrow ctxt, pprType tau]
+ sep [pprForAll tvs, pprThetaArrow (ctxt1 ++ ctxt2), pprType tau]
where
- (tvs, rho) = split1 [] ty
- (ctxt, tau) = split2 [] rho
-
- split1 tvs (ForAllTy tv ty) = split1 (tv:tvs) ty
- split1 tvs (NoteTy _ ty) = split1 tvs ty
- split1 tvs ty = (reverse tvs, ty)
+ (tvs, ctxt1, rho) = split1 [] [] ty
+ (ctxt2, tau) = split2 [] rho
+
+ -- We need to be extra careful here as equality constraints will occur as
+ -- type variables with an equality kind. So, while collecting quantified
+ -- variables, we separate the coercion variables out and turn them into
+ -- equality predicates.
+ split1 tvs eqs (ForAllTy tv ty)
+ | isCoVar tv = split1 tvs (eq:eqs) ty
+ | otherwise = split1 (tv:tvs) eqs ty
+ where
+ PredTy eq = tyVarKind tv
+ split1 tvs eqs (NoteTy _ ty) = split1 tvs eqs ty
+ split1 tvs eqs ty = (reverse tvs, reverse eqs, ty)
split2 ps (NoteTy _ arg -- Rather a disgusting case
`FunTy` res) = split2 ps (arg `FunTy` res)
| isTupleTyCon tc && tyConArity tc == length tys
= tupleParens (tupleTyConBoxity tc) (sep (punctuate comma (map pprType tys)))
| otherwise
- = maybeParen p TyConPrec $
- ppr_tc tc <+> sep (map (ppr_type TyConPrec) tys)
+ = ppr_type_app p (getName tc) (ppr_naked_tc tc) tys
+
+ppr_type_app :: Prec -> Name -> SDoc -> [Type] -> SDoc
+ppr_type_app p tc pp_tc tys
+ | is_sym_occ -- Print infix if possible
+ , [ty1,ty2] <- tys -- We know nothing of precedence though
+ = maybeParen p FunPrec (sep [ppr_type FunPrec ty1,
+ pp_tc <+> ppr_type FunPrec ty2])
+ | otherwise
+ = maybeParen p TyConPrec (hang paren_tc 2 (sep (map pprParendType tys)))
+ where
+ is_sym_occ = isSymOcc (getOccName tc)
+ paren_tc | is_sym_occ = parens pp_tc
+ | otherwise = pp_tc
ppr_tc :: TyCon -> SDoc
-ppr_tc tc = parenSymOcc (getOccName tc) (pp_nt_debug <> ppr tc)
+ppr_tc tc = parenSymOcc (getOccName tc) (ppr_naked_tc tc)
+
+ppr_naked_tc :: TyCon -> SDoc -- No brackets for SymOcc
+ppr_naked_tc tc
+ = pp_nt_debug <> ppr tc
where
pp_nt_debug | isNewTyCon tc = ifPprDebug (if isRecursiveTyCon tc
then ptext SLIT("<recnt>")
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