Small rearrangements

[ghc-hetmet.git] / compiler / hsSyn / HsExpr.lhs

diff --git a/compiler/hsSyn/HsExpr.lhs b/compiler/hsSyn/HsExpr.lhs
index 11b4df3..9161d46 100644 (file)
--- a/compiler/hsSyn/HsExpr.lhs
+++ b/compiler/hsSyn/HsExpr.lhs
@@ -326,8 +326,8 @@ ppr_expr (OpApp e1 op fixity e2)
       HsVar v -> pp_infixly v
       _              -> pp_prefixly
   where
-    pp_e1 = pprParendExpr e1           -- Add parens to make precedence clear
-    pp_e2 = pprParendExpr e2
+    pp_e1 = pprDebugParendExpr e1   -- In debug mode, add parens 
+    pp_e2 = pprDebugParendExpr e2   -- to make precedence clear
 
     pp_prefixly
       = hang (ppr op) 2 (sep [pp_e1, pp_e2])
@@ -335,14 +335,14 @@ ppr_expr (OpApp e1 op fixity e2)
     pp_infixly v
       = sep [nest 2 pp_e1, pprInfix v, nest 2 pp_e2]
 
-ppr_expr (NegApp e _) = char '-' <+> pprParendExpr e
+ppr_expr (NegApp e _) = char '-' <+> pprDebugParendExpr e
 
 ppr_expr (SectionL expr op)
   = case unLoc op of
       HsVar v -> pp_infixly v
       _              -> pp_prefixly
   where
-    pp_expr = pprParendExpr expr
+    pp_expr = pprDebugParendExpr expr
 
     pp_prefixly = hang (hsep [text " \\ x_ ->", ppr op])
                       4 (hsep [pp_expr, ptext SLIT("x_ )")])
@@ -353,7 +353,7 @@ ppr_expr (SectionR op expr)
       HsVar v -> pp_infixly v
       _              -> pp_prefixly
   where
-    pp_expr = pprParendExpr expr
+    pp_expr = pprDebugParendExpr expr
 
     pp_prefixly = hang (hsep [text "( \\ x_ ->", ppr op, ptext SLIT("x_")])
                       4 ((<>) pp_expr rparen)
@@ -394,10 +394,10 @@ ppr_expr (ExplicitTuple exprs boxity)
   = tupleParens boxity (sep (punctuate comma (map ppr_lexpr exprs)))
 
 ppr_expr (RecordCon con_id con_expr rbinds)
-  = pp_rbinds (ppr con_id) rbinds
+  = hang (ppr con_id) 2 (ppr rbinds)
 
 ppr_expr (RecordUpd aexp rbinds _ _ _)
-  = pp_rbinds (pprParendExpr aexp) rbinds
+  = hang (pprParendExpr aexp) 2 (ppr rbinds)
 
 ppr_expr (ExprWithTySig expr sig)
   = hang (nest 2 (ppr_lexpr expr) <+> dcolon)
@@ -473,8 +473,23 @@ pa_brackets :: SDoc -> SDoc
 pa_brackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]")    
 \end{code}
 
-Parenthesize unless very simple:
+HsSyn records exactly where the user put parens, with HsPar.
+So generally speaking we print without adding any parens.
+However, some code is internally generated, and in some places
+parens are absolutely required; so for these places we use
+pprParendExpr (but don't print double parens of course).
+
+For operator applications we don't add parens, because the oprerator
+fixities should do the job, except in debug mode (-dppr-debug) so we
+can see the structure of the parse tree.
+
 \begin{code}
+pprDebugParendExpr :: OutputableBndr id => LHsExpr id -> SDoc
+pprDebugParendExpr expr
+  = getPprStyle (\sty ->
+    if debugStyle sty then pprParendExpr expr
+                     else pprLExpr      expr)
+  
 pprParendExpr :: OutputableBndr id => LHsExpr id -> SDoc
 pprParendExpr expr
   = let
@@ -483,17 +498,19 @@ 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
@@ -582,17 +599,7 @@ data HsCmdTop id
 %************************************************************************
 
 \begin{code}
-data HsRecordBinds id = HsRecordBinds [(Located id, LHsExpr id)]
-
-recBindFields :: HsRecordBinds id -> [id]
-recBindFields (HsRecordBinds rbinds) = [unLoc field | (field,_) <- rbinds]
-
-pp_rbinds :: OutputableBndr id => SDoc -> HsRecordBinds id -> SDoc
-pp_rbinds thing (HsRecordBinds rbinds)
-  = hang thing 
-        4 (braces (pprDeeperList sep (punctuate comma (map (pp_rbind) rbinds))))
-  where
-    pp_rbind (v, e) = hsep [pprBndr LetBind (unLoc v), char '=', ppr e]
+type HsRecordBinds id = HsRecFields id (LHsExpr id)
 \end{code}
 
 
@@ -936,7 +943,12 @@ 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}