X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FTypeRep.lhs;h=111d194be43567a7d2ae64330e7256e58ea61acc;hb=b88025eabcd83f65d1d81f09272f5172f06a60e7;hp=7bb863a210e37841c77a8b7be7a6dac00985a439;hpb=0065d5ab628975892cea1ec7303f968c3338cbe1;p=ghc-hetmet.git diff --git a/compiler/types/TypeRep.lhs b/compiler/types/TypeRep.lhs index 7bb863a..111d194 100644 --- a/compiler/types/TypeRep.lhs +++ b/compiler/types/TypeRep.lhs @@ -1,4 +1,5 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1998 % \section[TypeRep]{Type - friends' interface} @@ -14,13 +15,29 @@ module TypeRep ( funTyCon, -- Pretty-printing - pprType, pprParendType, pprTyThingCategory, - pprPred, pprTheta, pprThetaArrow, pprClassPred, + pprType, pprParendType, pprTyThingCategory, + pprPred, pprTheta, pprForAll, pprThetaArrow, pprClassPred, - -- Re-export fromKind + -- Kinds liftedTypeKind, unliftedTypeKind, openTypeKind, - isLiftedTypeKind, isUnliftedTypeKind, isOpenTypeKind, - mkArrowKind, mkArrowKinds, + argTypeKind, ubxTupleKind, + isLiftedTypeKindCon, isLiftedTypeKind, + mkArrowKind, mkArrowKinds, isCoercionKind, + + -- Kind constructors... + liftedTypeKindTyCon, openTypeKindTyCon, unliftedTypeKindTyCon, + argTypeKindTyCon, ubxTupleKindTyCon, + + -- And their names + unliftedTypeKindTyConName, openTypeKindTyConName, + ubxTupleKindTyConName, argTypeKindTyConName, + liftedTypeKindTyConName, + + -- Super Kinds + tySuperKind, coSuperKind, + isTySuperKind, isCoSuperKind, + tySuperKindTyCon, coSuperKindTyCon, + pprKind, pprParendKind ) where @@ -29,17 +46,16 @@ module TypeRep ( import {-# SOURCE #-} DataCon( DataCon, dataConName ) -- friends: -import Kind -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 ) -import Class ( Class ) +import Var +import VarSet +import Name +import OccName +import BasicTypes +import TyCon +import Class -- others -import PrelNames ( gHC_PRIM, funTyConKey, listTyConKey, parrTyConKey, hasKey ) +import PrelNames import Outputable \end{code} @@ -170,18 +186,30 @@ data Type TyVar Type - | PredTy -- A high level source type - PredType -- ...can be expanded to a representation type... + | PredTy -- The type of evidence for a type predictate + PredType -- See Note [PredTy], and Note [Equality predicates] + -- NB: A PredTy (EqPred _ _) can appear only as the kind + -- of a coercion variable; never as the argument or result + -- of a FunTy (unlike ClassP, IParam) | NoteTy -- A type with a note attached TyNote Type -- The expanded version +type Kind = Type -- Invariant: a kind is always + -- FunTy k1 k2 + -- or TyConApp PrimTyCon [...] + -- or TyVar kv (during inference only) + -- or ForAll ... (for top-level coercions) + +type SuperKind = Type -- Invariant: a super kind is always + -- TyConApp SuperKindTyCon ... + data TyNote = FTVNote TyVarSet -- The free type variables of the noted expression \end{code} ------------------------------------- - Source types + Note [PredTy] A type of the form PredTy p @@ -204,6 +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) type ThetaType = [PredType] \end{code} @@ -220,6 +249,24 @@ The predicate really does turn into a real extra argument to the function. If the argument has type (PredTy p) then the predicate p is represented by evidence (a dictionary, for example, of type (predRepTy p). +Note [Equality predicates] +~~~~~~~~~~~~~~~~~~~~~~~~~~ + forall a b. (a :=: S b) => a -> b +could be represented by + ForAllTy a (ForAllTy b (FunTy (PredTy (EqPred a (S b))) ...)) +OR + ForAllTy a (ForAllTy b (ForAllTy (c::PredTy (EqPred a (S b))) ...)) + +The latter is what we do. (Unlike for class and implicit parameter +constraints, which do use FunTy.) + +Reason: + * FunTy is always a *value* function + * ForAllTy is discarded at runtime + +We often need to make a "wildcard" (c::PredTy..). We always use the same +name (wildCoVarName), since it's not mentioned. + %************************************************************************ %* * @@ -256,13 +303,16 @@ instance NamedThing TyThing where -- Can't put this with the type %************************************************************************ %* * -\subsection{Wired-in type constructors + Wired-in type constructors %* * %************************************************************************ We define a few wired-in type constructors here to avoid module knots \begin{code} +-------------------------- +-- First the TyCons... + funTyCon = mkFunTyCon funTyConName (mkArrowKinds [argTypeKind, openTypeKind] liftedTypeKind) -- You might think that (->) should have type (?? -> ? -> *), and you'd be right -- But if we do that we get kind errors when saying @@ -272,15 +322,89 @@ funTyCon = mkFunTyCon funTyConName (mkArrowKinds [argTypeKind, openTypeKind] lif -- the kind sub-typing does. Sigh. It really only matters if you use (->) in -- a prefix way, thus: (->) Int# Int#. And this is unusual. -funTyConName = mkWiredInName gHC_PRIM - (mkOccNameFS tcName FSLIT("(->)")) - funTyConKey - Nothing -- No parent object - (ATyCon funTyCon) -- Relevant TyCon - BuiltInSyntax + +tySuperKindTyCon = mkSuperKindTyCon tySuperKindTyConName +coSuperKindTyCon = mkSuperKindTyCon coSuperKindTyConName + +liftedTypeKindTyCon = mkKindTyCon liftedTypeKindTyConName +openTypeKindTyCon = mkKindTyCon openTypeKindTyConName +unliftedTypeKindTyCon = mkKindTyCon unliftedTypeKindTyConName +ubxTupleKindTyCon = mkKindTyCon ubxTupleKindTyConName +argTypeKindTyCon = mkKindTyCon argTypeKindTyConName + +mkKindTyCon :: Name -> TyCon +mkKindTyCon name = mkVoidPrimTyCon name tySuperKind 0 + +-------------------------- +-- ... and now their names + +tySuperKindTyConName = mkPrimTyConName FSLIT("BOX") tySuperKindTyConKey tySuperKindTyCon +coSuperKindTyConName = mkPrimTyConName FSLIT("COERCION") coSuperKindTyConKey coSuperKindTyCon +liftedTypeKindTyConName = mkPrimTyConName FSLIT("*") liftedTypeKindTyConKey liftedTypeKindTyCon +openTypeKindTyConName = mkPrimTyConName FSLIT("?") openTypeKindTyConKey openTypeKindTyCon +unliftedTypeKindTyConName = mkPrimTyConName FSLIT("#") unliftedTypeKindTyConKey unliftedTypeKindTyCon +ubxTupleKindTyConName = mkPrimTyConName FSLIT("(#)") ubxTupleKindTyConKey ubxTupleKindTyCon +argTypeKindTyConName = mkPrimTyConName FSLIT("??") argTypeKindTyConKey argTypeKindTyCon +funTyConName = mkPrimTyConName FSLIT("(->)") funTyConKey funTyCon + +mkPrimTyConName occ key tycon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ) + key + (ATyCon tycon) + BuiltInSyntax + -- All of the super kinds and kinds are defined in Prim and use BuiltInSyntax, + -- because they are never in scope in the source + +------------------ +-- We also need Kinds and SuperKinds, locally and in TyCon + +kindTyConType :: TyCon -> Type +kindTyConType kind = TyConApp kind [] + +liftedTypeKind = kindTyConType liftedTypeKindTyCon +unliftedTypeKind = kindTyConType unliftedTypeKindTyCon +openTypeKind = kindTyConType openTypeKindTyCon +argTypeKind = kindTyConType argTypeKindTyCon +ubxTupleKind = kindTyConType ubxTupleKindTyCon + +mkArrowKind :: Kind -> Kind -> Kind +mkArrowKind k1 k2 = FunTy k1 k2 + +mkArrowKinds :: [Kind] -> Kind -> Kind +mkArrowKinds arg_kinds result_kind = foldr mkArrowKind result_kind arg_kinds + +tySuperKind, coSuperKind :: SuperKind +tySuperKind = kindTyConType tySuperKindTyCon +coSuperKind = kindTyConType coSuperKindTyCon + +isTySuperKind (NoteTy _ ty) = isTySuperKind ty +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 + +------------------- +-- 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} + %************************************************************************ %* * \subsection{The external interface} @@ -312,6 +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] pprClassPred :: Class -> [Type] -> SDoc pprClassPred clas tys = parenSymOcc (getOccName clas) (ppr clas) @@ -338,9 +463,12 @@ instance Outputable name => OutputableBndr (IPName name) where ------------------ -- OK, here's the main printer +pprKind = pprType +pprParendKind = pprParendType + 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("")) <> (ppr pred) ppr_type p (NoteTy other ty2) = ppr_type p ty2 ppr_type p (TyConApp tc tys) = ppr_tc_app p tc tys @@ -382,6 +510,12 @@ ppr_tc_app p tc [] ppr_tc_app p tc [ty] | tc `hasKey` listTyConKey = brackets (pprType ty) | tc `hasKey` parrTyConKey = ptext SLIT("[:") <> pprType ty <> ptext SLIT(":]") + | tc `hasKey` liftedTypeKindTyConKey = ptext SLIT("*") + | tc `hasKey` unliftedTypeKindTyConKey = ptext SLIT("#") + | tc `hasKey` openTypeKindTyConKey = ptext SLIT("(?)") + | tc `hasKey` ubxTupleKindTyConKey = ptext SLIT("(#)") + | tc `hasKey` argTypeKindTyConKey = ptext SLIT("??") + ppr_tc_app p tc tys | isTupleTyCon tc && tyConArity tc == length tys = tupleParens (tupleTyConBoxity tc) (sep (punctuate comma (map pprType tys)))