Minor refactoring: give an explicit name to the pretty-printing function for TyThing...

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

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index 8f23a35..c1e0544 100644 (file)
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -6,6 +6,13 @@
 Type - public 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 Type (
         -- re-exports from TypeRep
        TyThing(..), Type, PredType(..), ThetaType, 
@@ -67,6 +74,9 @@ module Type (
        tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
        typeKind, addFreeTyVars,
 
+        -- Type families
+        tyFamInsts,
+
        -- Tidying up for printing
        tidyType,      tidyTypes,
        tidyOpenType,  tidyOpenTypes,
@@ -77,7 +87,7 @@ module Type (
 
        -- Comparison
        coreEqType, tcEqType, tcEqTypes, tcCmpType, tcCmpTypes, 
-       tcEqPred, tcCmpPred, tcEqTypeX, 
+       tcEqPred, tcCmpPred, tcEqTypeX, tcPartOfType, tcPartOfPred,
 
        -- Seq
        seqType, seqTypes,
@@ -95,7 +105,7 @@ module Type (
        substPred, substTyVar, substTyVars, substTyVarBndr, deShadowTy, lookupTyVar,
 
        -- Pretty-printing
-       pprType, pprParendType, pprTypeApp, pprTyThingCategory, pprForAll,
+       pprType, pprParendType, pprTypeApp, pprTyThingCategory, pprTyThing, pprForAll,
        pprPred, pprTheta, pprThetaArrow, pprClassPred, pprKind, pprParendKind
     ) where
 
@@ -408,8 +418,14 @@ splitNewTyConApp_maybe (FunTy arg res)   = Just (funTyCon, [arg,res])
 splitNewTyConApp_maybe other         = Nothing
 
 newTyConInstRhs :: TyCon -> [Type] -> Type
-newTyConInstRhs tycon tys =
-    let (tvs, ty) = newTyConRhs tycon in substTyWith tvs tys ty
+-- Unwrap one 'layer' of newtype
+-- Use the eta'd version if possible
+newTyConInstRhs tycon tys 
+    = ASSERT2( equalLength tvs tys1, ppr tycon $$ ppr tys $$ ppr tvs )
+      mkAppTys (substTyWith tvs tys1 ty) tys2
+  where
+    (tvs, ty)    = newTyConEtadRhs tycon
+    (tys1, tys2) = splitAtList tvs tys
 \end{code}
 
 
@@ -696,6 +712,28 @@ addFreeTyVars ty                        = NoteTy (FTVNote (tyVarsOfType ty)) ty
 
 %************************************************************************
 %*                                                                     *
+\subsection{Type families}
+%*                                                                     *
+%************************************************************************
+
+Type family instances occuring in a type after expanding synonyms.
+
+\begin{code}
+tyFamInsts :: Type -> [(TyCon, [Type])]
+tyFamInsts ty 
+  | Just exp_ty <- tcView ty    = tyFamInsts exp_ty
+tyFamInsts (TyVarTy _)          = []
+tyFamInsts (TyConApp tc tys) 
+  | isOpenSynTyCon tc           = [(tc, tys)]
+  | otherwise                   = concat (map tyFamInsts tys)
+tyFamInsts (FunTy ty1 ty2)      = tyFamInsts ty1 ++ tyFamInsts ty2
+tyFamInsts (AppTy ty1 ty2)      = tyFamInsts ty1 ++ tyFamInsts ty2
+tyFamInsts (ForAllTy _ ty)      = tyFamInsts ty
+\end{code}
+
+
+%************************************************************************
+%*                                                                     *
 \subsection{TidyType}
 %*                                                                     *
 %************************************************************************
@@ -961,6 +999,27 @@ tcEqTypeX :: RnEnv2 -> Type -> Type -> Bool
 tcEqTypeX env t1 t2 = isEqual $ cmpTypeX env t1 t2
 \end{code}
 
+Checks whether the second argument is a subterm of the first.  (We don't care
+about binders, as we are only interested in syntactic subterms.)
+
+\begin{code}
+tcPartOfType :: Type -> Type -> Bool
+tcPartOfType t1              t2 = tcEqType t1 t2
+tcPartOfType t1              t2 
+  | Just t2' <- tcView t2       = tcPartOfType t1 t2'
+tcPartOfType t1 (ForAllTy _ t2) = tcPartOfType t1 t2
+tcPartOfType t1 (AppTy s2 t2)   = tcPartOfType t1 s2 || tcPartOfType t1 t2
+tcPartOfType t1 (FunTy s2 t2)   = tcPartOfType t1 s2 || tcPartOfType t1 t2
+tcPartOfType t1 (PredTy p2)     = tcPartOfPred t1 p2
+tcPartOfType t1 (TyConApp _ ts) = any (tcPartOfType t1) ts
+tcPartOfType t1 (NoteTy _ t2)   = tcPartOfType t1 t2
+
+tcPartOfPred :: Type -> PredType -> Bool
+tcPartOfPred t1 (IParam _ t2)  = tcPartOfType t1 t2
+tcPartOfPred t1 (ClassP _ ts)  = any (tcPartOfType t1) ts
+tcPartOfPred t1 (EqPred s2 t2) = tcPartOfType t1 s2 || tcPartOfType t1 t2
+\end{code}
+
 Now here comes the real worker
 
 \begin{code}
@@ -1467,8 +1526,6 @@ isSuperKind other = False
 isKind :: Kind -> Bool
 isKind k = isSuperKind (typeKind k)
 
-
-
 isSubKind :: Kind -> Kind -> Bool
 -- (k1 `isSubKind` k2) checks that k1 <: k2
 isSubKind (TyConApp kc1 []) (TyConApp kc2 []) = kc1 `isSubKindCon` kc2