Tidy up the treatment of dead binders

[ghc-hetmet.git] / compiler / coreSyn / PprCore.lhs

diff --git a/compiler/coreSyn/PprCore.lhs b/compiler/coreSyn/PprCore.lhs
index 39d5b35..d641a9e 100644 (file)
--- a/compiler/coreSyn/PprCore.lhs
+++ b/compiler/coreSyn/PprCore.lhs
@@ -248,7 +248,7 @@ instance OutputableBndr Var where
 
 pprCoreBinder :: BindingSite -> Var -> SDoc
 pprCoreBinder LetBind binder
-  | isTyVar binder = pprTypedBinder binder
+  | isTyVar binder = pprKindedTyVarBndr binder
   | otherwise
   = vcat [sig, pprIdDetails binder, pragmas]
   where
@@ -256,7 +256,15 @@ pprCoreBinder LetBind binder
     pragmas = ppIdInfo binder (idInfo binder)
 
 -- Lambda bound type variables are preceded by "@"
-pprCoreBinder LambdaBind bndr = parens (pprTypedBinder bndr)
+pprCoreBinder LambdaBind bndr 
+  | isDeadBinder bndr
+  = getPprStyle $ \ sty ->
+    if debugStyle sty then
+       parens (pprTypedBinder bndr)
+    else
+       char '_'
+  | otherwise
+  = parens (pprTypedBinder bndr)
 
 -- Case bound things don't get a signature or a herald, unless we have debug on
 pprCoreBinder CaseBind bndr 
@@ -264,7 +272,8 @@ pprCoreBinder CaseBind bndr
     if debugStyle sty then
        parens (pprTypedBinder bndr)
     else
-       pprUntypedBinder bndr
+       if isDeadBinder bndr then char '_'
+       else pprUntypedBinder bndr
 
 pprUntypedBinder :: Var -> SDoc
 pprUntypedBinder binder
@@ -272,19 +281,19 @@ pprUntypedBinder binder
   | otherwise      = pprIdBndr binder
 
 pprTypedBinder :: Var -> SDoc
+-- Print binder with a type or kind signature (not paren'd)
 pprTypedBinder binder
-  | isTyVar binder  = ptext (sLit "@") <+> pprTyVarBndr binder
+  | isTyVar binder  = pprKindedTyVarBndr binder
   | otherwise      = pprIdBndr binder <+> dcolon <+> pprType (idType binder)
 
-pprTyVarBndr :: TyVar -> SDoc
-pprTyVarBndr tyvar
-  = getPprStyle $ \ sty ->
-    if debugStyle sty then
-        hsep [ppr tyvar, dcolon, pprParendKind kind]
-               -- See comments with ppDcolon in PprCore.lhs
-    else
-        ppr tyvar
+pprKindedTyVarBndr :: TyVar -> SDoc
+-- Print a type variable binder with its kind (but not if *)
+pprKindedTyVarBndr tyvar
+  = ptext (sLit "@") <+> ppr tyvar <> opt_kind
   where
+    opt_kind   -- Print the kind if not *
+       | isLiftedTypeKind kind = empty
+       | otherwise = dcolon <> pprKind kind
     kind = tyVarKind tyvar
 
 -- pprIdBndr does *not* print the type