X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FhsSyn%2FHsExpr.lhs;h=44d9b436c3bd8adca739a2ea071cb68410e7dd1f;hb=8181524071b7df3d4982349a43840456ef0747b4;hp=a5f5f3001fc6b20df355b60a1f82182b36f67e4c;hpb=6f1d5899f59f268d5390ec12af9c9f2a529b56ef;p=ghc-hetmet.git

diff --git a/compiler/hsSyn/HsExpr.lhs b/compiler/hsSyn/HsExpr.lhs
index a5f5f30..44d9b43 100644
--- a/compiler/hsSyn/HsExpr.lhs
+++ b/compiler/hsSyn/HsExpr.lhs
@@ -285,8 +285,18 @@ pprLExpr :: OutputableBndr id => LHsExpr id -> SDoc
 pprLExpr (L _ e) = pprExpr e
 
 pprExpr :: OutputableBndr id => HsExpr id -> SDoc
-pprExpr e | isAtomicHsExpr e = ppr_expr e	-- Never replace 'x' by "..."
-	  | otherwise	     = pprDeeper (ppr_expr e)
+pprExpr e | isAtomicHsExpr e || isQuietHsExpr e =            ppr_expr e
+          | otherwise                           = pprDeeper (ppr_expr e)
+
+isQuietHsExpr :: HsExpr id -> Bool
+-- Parentheses do display something, but it gives little info and
+-- if we go deeper when we go inside them then we get ugly things
+-- like (...)
+isQuietHsExpr (HsPar _) = True
+-- applications don't display anything themselves
+isQuietHsExpr (HsApp _ _) = True
+isQuietHsExpr (OpApp _ _ _ _) = True
+isQuietHsExpr _ = False
 
 pprBinds :: OutputableBndr id => HsLocalBinds id -> SDoc
 pprBinds b = pprDeeper (ppr b)
@@ -473,17 +483,19 @@ pprParendExpr expr
 	-- I think that is usually (always?) right
     in
     case unLoc expr of
-      HsLit l		-> pp_as_was
-      HsOverLit l 	-> pp_as_was
-      HsVar _		-> pp_as_was
-      HsIPVar _		-> pp_as_was
-      ExplicitList _ _  -> pp_as_was
-      ExplicitPArr _ _  -> pp_as_was
-      ExplicitTuple _ _	-> pp_as_was
-      HsPar _		-> pp_as_was
-      HsBracket _	-> pp_as_was
-      HsBracketOut _ []	-> pp_as_was
-      _			-> parens pp_as_was
+      HsLit l		   -> pp_as_was
+      HsOverLit l 	   -> pp_as_was
+      HsVar _		   -> pp_as_was
+      HsIPVar _		   -> pp_as_was
+      ExplicitList _ _     -> pp_as_was
+      ExplicitPArr _ _     -> pp_as_was
+      ExplicitTuple _ _	   -> pp_as_was
+      HsPar _		   -> pp_as_was
+      HsBracket _	   -> pp_as_was
+      HsBracketOut _ []	   -> pp_as_was
+      HsDo sc _ _ _
+       | isListCompExpr sc -> pp_as_was
+      _			   -> parens pp_as_was
 
 isAtomicHsExpr :: HsExpr id -> Bool	-- A single token
 isAtomicHsExpr (HsVar {})     = True
@@ -684,11 +696,9 @@ pprMatch ctxt (Match pats maybe_ty grhss)
 
 pprGRHSs :: OutputableBndr id => HsMatchContext id -> GRHSs id -> SDoc
 pprGRHSs ctxt (GRHSs grhss binds)
-  = pprDeeper
-    (vcat (map (pprGRHS ctxt . unLoc) grhss)
-      $$
-     if isEmptyLocalBinds binds then empty
-     else text "where" $$ nest 4 (pprBinds binds))
+  = vcat (map (pprGRHS ctxt . unLoc) grhss)
+ $$ if isEmptyLocalBinds binds then empty
+                               else text "where" $$ nest 4 (pprBinds binds)
 
 pprGRHS :: OutputableBndr id => HsMatchContext id -> GRHS id -> SDoc
 
@@ -928,7 +938,12 @@ data HsStmtContext id
 isDoExpr :: HsStmtContext id -> Bool
 isDoExpr DoExpr      = True
 isDoExpr (MDoExpr _) = True
-isDoExpr other       = False
+isDoExpr _           = False
+
+isListCompExpr :: HsStmtContext id -> Bool
+isListCompExpr ListComp = True
+isListCompExpr PArrComp = True
+isListCompExpr _        = False
 \end{code}
 
 \begin{code}