[project @ 2002-01-07 12:26:49 by simonpj]

[ghc-hetmet.git] / ghc / compiler / basicTypes / NewDemand.lhs

diff --git a/ghc/compiler/basicTypes/NewDemand.lhs b/ghc/compiler/basicTypes/NewDemand.lhs
index df46950..ea314d5 100644 (file)
--- a/ghc/compiler/basicTypes/NewDemand.lhs
+++ b/ghc/compiler/basicTypes/NewDemand.lhs
@@ -126,8 +126,12 @@ instance Outputable Demand where
 instance Outputable Demands where
     ppr (Poly Abs) = empty
     ppr (Poly d)   = parens (ppr d <> char '*')
-    ppr (Prod ds) | all isAbsent ds = empty
-                 | otherwise       = parens (hcat (map ppr ds))
+    ppr (Prod ds)  = parens (hcat (map ppr ds))
+       -- At one time I printed U(AAA) as U, but that
+       -- confuses (Poly Abs) with (Prod AAA), and the
+       -- worker/wrapper generation differs slightly for these two
+       -- [Reason: in the latter case we can avoid passing the arg;
+       --  see notes with WwLib.mkWWstr_one.]
 \end{code}