Make type-tidying work for coercion variables

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

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index d81278a..fe70716 100644 (file)
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -55,7 +55,7 @@ module Type (
 
        -- Source types
        predTypeRep, mkPredTy, mkPredTys,
-       tyConOrigHead,
+       tyConOrigHead, pprSourceTyCon,
 
        -- Newtypes
        splitRecNewType_maybe, newTyConInstRhs,
@@ -95,7 +95,7 @@ module Type (
        substPred, substTyVar, substTyVars, substTyVarBndr, deShadowTy, lookupTyVar,
 
        -- Pretty-printing
-       pprType, pprParendType, pprTyThingCategory, pprForAll,
+       pprType, pprParendType, pprTypeApp, pprTyThingCategory, pprForAll,
        pprPred, pprTheta, pprThetaArrow, pprClassPred, pprKind, pprParendKind
     ) where
 
@@ -609,6 +609,16 @@ tyConOrigHead :: TyCon -> (TyCon, [Type])
 tyConOrigHead tycon = case tyConFamInst_maybe tycon of
                        Nothing      -> (tycon, mkTyVarTys (tyConTyVars tycon))
                        Just famInst -> famInst
+
+-- Pretty prints a tycon, using the family instance in case of a
+-- representation tycon.  For example
+--     e.g.  data T [a] = ...
+-- In that case we want to print `T [a]', where T is the family TyCon
+pprSourceTyCon tycon 
+  | Just (repTyCon, tys) <- tyConFamInst_maybe tycon
+  = ppr $ repTyCon `TyConApp` tys             -- can't be FunTyCon
+  | otherwise
+  = ppr tycon
 \end{code}
 
 
@@ -723,13 +733,17 @@ It doesn't change the uniques at all, just the print names.
 
 \begin{code}
 tidyTyVarBndr :: TidyEnv -> TyVar -> (TidyEnv, TyVar)
-tidyTyVarBndr (tidy_env, subst) tyvar
+tidyTyVarBndr env@(tidy_env, subst) tyvar
   = case tidyOccName tidy_env (getOccName name) of
-      (tidy', occ') ->         ((tidy', subst'), tyvar')
-                   where
-                       subst' = extendVarEnv subst tyvar tyvar'
-                       tyvar' = setTyVarName tyvar name'
-                       name'  = tidyNameOcc name occ'
+      (tidy', occ') -> ((tidy', subst'), tyvar'')
+       where
+         subst' = extendVarEnv subst tyvar tyvar''
+         tyvar' = setTyVarName tyvar name'
+         name'  = tidyNameOcc name occ'
+               -- Don't forget to tidy the kind for coercions!
+         tyvar'' | isCoVar tyvar = setTyVarKind tyvar' kind'
+                 | otherwise     = tyvar'
+         kind'  = tidyType env (tyVarKind tyvar)
   where
     name = tyVarName tyvar