[project @ 1996-04-07 15:41:24 by partain]

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

diff --git a/ghc/compiler/hsSyn/HsPat.lhs b/ghc/compiler/hsSyn/HsPat.lhs
index 11e4d26..9cf88be 100644 (file)
--- a/ghc/compiler/hsSyn/HsPat.lhs
+++ b/ghc/compiler/hsSyn/HsPat.lhs
@@ -47,6 +47,12 @@ data InPat name
   | ConOpPatIn     (InPat name)
                    name
                    (InPat name)
+
+  -- We preserve prefix negation and parenthesis for the precedence parser.
+
+  | NegPatIn       (InPat name)        -- negated pattern
+  | ParPatIn        (InPat name)       -- parenthesised pattern
+
   | ListPatIn      [InPat name]        -- syntactic list
                                        -- must have >= 1 elements
   | TuplePatIn     [InPat name]        -- tuple
@@ -124,8 +130,15 @@ pprInPat sty (ConPatIn c pats)
 pprInPat sty (ConOpPatIn pat1 op pat2)
  = ppBesides [ppLparen, ppr sty pat1, ppSP, ppr sty op, ppSP, ppr sty pat2, ppRparen]
 
--- ToDo: use pprOp to print op (but this involves fiddling various
--- contexts & I'm lazy...); *PatIns are *rarely* printed anyway... (WDP)
+       -- ToDo: use pprOp to print op (but this involves fiddling various
+       -- contexts & I'm lazy...); *PatIns are *rarely* printed anyway... (WDP)
+
+pprInPat sty (NegPatIn pat)
+  = ppBeside (ppChar '-') (ppParens (pprInPat sty pat))
+
+pprInPat sty (ParPatIn pat)
+  = ppParens (pprInPat sty pat)
+
 
 pprInPat sty (ListPatIn pats)
   = ppBesides [ppLbrack, interpp'SP sty pats, ppRbrack]
@@ -185,7 +198,7 @@ pprOutPat sty (DictPat dicts methods)
          ppBesides [ppBracket (interpp'SP sty methods), ppRparen]]
 
 pprConPatTy sty ty
- = ppBesides [ppLparen, ppr sty ty, ppRparen]
+ = ppParens (ppr sty ty)
 \end{code}
 
 %************************************************************************