From: simonpj@microsoft.com <unknown>
Date: Wed, 16 Dec 2009 08:45:13 +0000 (+0000)
Subject: Fix a long-standing infelicity in the type pretty printer
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=0e73a9fbdc8555ffb948cfd72401a700b122c395

Fix a long-standing infelicity in the type pretty printer

We weren't parenthesising
   List (C Int)
correctly, when (C Int) is a PredTy
---

diff --git a/compiler/types/TypeRep.lhs b/compiler/types/TypeRep.lhs
index a5176ce..1660267 100644
--- a/compiler/types/TypeRep.lhs
+++ b/compiler/types/TypeRep.lhs
@@ -471,7 +471,8 @@ ppr_type :: Prec -> Type -> SDoc
 ppr_type _ (TyVarTy tv)		-- Note [Infix type variables]
   | isSymOcc (getOccName tv)  = parens (ppr tv)
   | otherwise		      = ppr tv
-ppr_type _ (PredTy pred)      = ifPprDebug (ptext (sLit "<pred>")) <> (ppr pred)
+ppr_type p (PredTy pred)      = maybeParen p TyConPrec $
+                                ifPprDebug (ptext (sLit "<pred>")) <> (ppr pred)
 ppr_type p (TyConApp tc tys)  = ppr_tc_app p tc tys
 
 ppr_type p (AppTy t1 t2) = maybeParen p TyConPrec $