Add several new record features

[ghc-hetmet.git] / compiler / types / TypeRep.lhs

diff --git a/compiler/types/TypeRep.lhs b/compiler/types/TypeRep.lhs
index 9110d68..cc8e4be 100644 (file)
--- 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}
@@ -14,14 +15,15 @@ module TypeRep (
        funTyCon,
 
        -- Pretty-printing
-       pprType, pprParendType, pprTyThingCategory,
-       pprPred, pprTheta, pprThetaArrow, pprClassPred,
+       pprType, pprParendType, pprTypeApp,
+       pprTyThingCategory, 
+       pprPred, pprTheta, pprForAll, pprThetaArrow, pprClassPred,
 
        -- Kinds
        liftedTypeKind, unliftedTypeKind, openTypeKind,
         argTypeKind, ubxTupleKind,
        isLiftedTypeKindCon, isLiftedTypeKind,
-       mkArrowKind, mkArrowKinds,
+       mkArrowKind, mkArrowKinds, isCoercionKind,
 
         -- Kind constructors...
         liftedTypeKindTyCon, openTypeKindTyCon, unliftedTypeKindTyCon,
@@ -43,24 +45,18 @@ module TypeRep (
 #include "HsVersions.h"
 
 import {-# SOURCE #-} DataCon( DataCon, dataConName )
--- 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 )
-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 )
+import PrelNames
 import Outputable
 \end{code}
 
@@ -237,7 +233,7 @@ 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}
@@ -256,7 +252,7 @@ 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
@@ -391,14 +387,21 @@ isCoSuperKind (TyConApp kc []) = kc `hasKey` coSuperKindTyConKey
 isCoSuperKind other            = False
 
 -------------------
--- 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}
 
 
@@ -430,15 +433,17 @@ pprType, pprParendType :: Type -> SDoc
 pprType       ty = ppr_type TopPrec   ty
 pprParendType ty = ppr_type TyConPrec ty
 
+pprTypeApp :: SDoc -> [Type] -> SDoc
+pprTypeApp pp tys = hang pp 2 (sep (map pprParendType 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 = pprTypeApp (parenSymOcc (getOccName clas) (ppr clas)) tys
 
 pprTheta :: ThetaType -> SDoc
 pprTheta theta = parens (sep (punctuate comma (map pprPred theta)))
@@ -466,7 +471,7 @@ 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("<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
 
@@ -518,8 +523,7 @@ ppr_tc_app p tc tys
   | 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)
+  = maybeParen p TyConPrec (pprTypeApp (ppr_tc tc) tys)
 
 ppr_tc :: TyCon -> SDoc
 ppr_tc tc = parenSymOcc (getOccName tc) (pp_nt_debug <> ppr tc)