\begin{code}
module TypeRep (
Type(..), TyNote(..), -- Representation visible
- SourceType(..), IPName(..), -- to friends
+ SourceType(..), -- to friends
Kind, PredType, ThetaType, -- Synonyms
TyVarSubst,
liftedTypeKind, unliftedTypeKind, openTypeKind, -- :: KX
mkArrowKind, mkArrowKinds, -- :: KX -> KX -> KX
- usageKindCon, -- :: KX
- usageTypeKind, -- :: KX
- usOnceTyCon, usManyTyCon, -- :: $
- usOnce, usMany, -- :: $
-
funTyCon
) where
#include "HsVersions.h"
-- friends:
-import Var ( TyVar )
-import VarEnv
-import VarSet
-
-import Name ( Name )
-import TyCon ( TyCon, KindCon, mkFunTyCon, mkKindCon, mkSuperKindCon )
-import Class ( Class )
+import Var ( TyVar )
+import VarEnv ( TyVarEnv )
+import VarSet ( TyVarSet )
+import Name ( Name )
+import BasicTypes ( IPName )
+import TyCon ( TyCon, KindCon, mkFunTyCon, mkKindCon, mkSuperKindCon )
+import Class ( Class )
+import Binary
-- others
import PrelNames ( superKindName, superBoxityName, liftedConName,
unliftedConName, typeConName, openKindConName,
- usageKindConName, usOnceTyConName, usManyTyConName,
funTyConName
)
\end{code}
newtype application as a SourceType; instead as a TyConApp.
+NOTE: currently [March 02] we regard a newtype as 'recursive' if it's in a
+mutually recursive group. That's a bit conservative: only if there's a loop
+consisting only of newtypes do we need consider it as recursive. But it's
+not so easy to discover that, and the situation isn't that common.
+
+
%************************************************************************
%* *
\subsection{The data type}
| SourceTy -- A high level source type
SourceType -- ...can be expanded to a representation type...
- | UsageTy -- A usage-annotated type
- Type -- - Annotation of kind $ (i.e., usage annotation)
- Type -- - Annotated type
-
| NoteTy -- A type with a note attached
TyNote
Type -- The expanded version
| SynNote Type -- Used for type synonyms
-- The Type is always a TyConApp, and is the un-expanded form.
-- The type to which the note is attached is the expanded form.
-\end{code}
-INVARIANT: UsageTys are optional, but may *only* appear immediately
-under a FunTy (either argument), or at top-level of a Type permitted
-to be annotated (such as the type of an Id). NoteTys are transparent
-for the purposes of this rule.
+\end{code}
-------------------------------------
Source types
| NType TyCon [Type] -- A *saturated*, *non-recursive* newtype application
-- [See notes at top about newtypes]
-data IPName name
- = Dupable name -- ?x: you can freely duplicate this implicit parameter
- | MustSplit name -- %x: you must use the splitting function to duplicate it
- deriving( Eq, Ord ) -- Ord is used in the IP name cache finite map
- -- (used in HscTypes.OrigIParamCache)
- -- I sometimes thisnk this type should be in BasicTypes
-
type PredType = SourceType -- A subtype for predicates
type ThetaType = [PredType]
\end{code}
| Type liftedness -- (Type *) is printed as just *
-- (Type #) is printed as just #
- | UsageKind -- Printed '$'; used for usage annotations
-
| OpenKind -- Can be lifted or unlifted
-- Printed '?'
\begin{code}
liftedBoxity, unliftedBoxity :: Kind -- :: BX
-liftedBoxity = TyConApp (mkKindCon liftedConName superBoxity) []
+liftedBoxity = TyConApp liftedBoxityCon []
+unliftedBoxity = TyConApp unliftedBoxityCon []
-unliftedBoxity = TyConApp (mkKindCon unliftedConName superBoxity) []
+liftedBoxityCon = mkKindCon liftedConName superBoxity
+unliftedBoxityCon = mkKindCon unliftedConName superBoxity
\end{code}
------------------------------------------
-Define kinds: Type, Type *, Type #, OpenKind, and UsageKind
+Define kinds: Type, Type *, Type #, OpenKind
\begin{code}
typeCon :: KindCon -- :: BX -> KX
openKindCon = mkKindCon openKindConName superKind
openTypeKind = TyConApp openKindCon []
-
-usageKindCon = mkKindCon usageKindConName superKind
-usageTypeKind = TyConApp usageKindCon []
\end{code}
------------------------------------------
mkArrowKinds arg_kinds result_kind = foldr mkArrowKind result_kind arg_kinds
\end{code}
+-----------------------------------------------------------------------------
+Binary kinds for interface files
+
+\begin{code}
+instance Binary Kind where
+ put_ bh k@(TyConApp tc [])
+ | tc == openKindCon = putByte bh 0
+ put_ bh k@(TyConApp tc [TyConApp bc _])
+ | tc == typeCon && bc == liftedBoxityCon = putByte bh 2
+ | tc == typeCon && bc == unliftedBoxityCon = putByte bh 3
+ put_ bh (FunTy f a) = do putByte bh 4; put_ bh f; put_ bh a
+ put_ bh _ = error "Binary.put(Kind): strange-looking Kind"
+
+ get bh = do
+ b <- getByte bh
+ case b of
+ 0 -> return openTypeKind
+ 2 -> return liftedTypeKind
+ 3 -> return unliftedTypeKind
+ _ -> do f <- get bh; a <- get bh; return (FunTy f a)
+\end{code}
%************************************************************************
%* *
\begin{code}
funTyCon = mkFunTyCon funTyConName (mkArrowKinds [liftedTypeKind, liftedTypeKind] liftedTypeKind)
+ -- You might think that (->) should have type (? -> ? -> *), and you'd be right
+ -- But if we do that we get kind errors when saying
+ -- instance Control.Arrow (->)
+ -- becuase the expected kind is (*->*->*). The trouble is that the
+ -- expected/actual stuff in the unifier does not go contra-variant, whereas
+ -- the kind sub-typing does. Sigh. It really only matters if you use (->) in
+ -- a prefix way, thus: (->) Int# Int#. And this is unusual.
\end{code}
-------------------------------------------
-Usage tycons @.@ and @!@
-
-The usage tycons are of kind usageTypeKind (`$'). The types contain
-no values, and are used purely for usage annotation.
-
-\begin{code}
-usOnceTyCon = mkKindCon usOnceTyConName usageTypeKind
-usOnce = TyConApp usOnceTyCon []
-
-usManyTyCon = mkKindCon usManyTyConName usageTypeKind
-usMany = TyConApp usManyTyCon []
-\end{code}
projects / ghc-hetmet.git / blobdiff