Minor refactoring

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

diff --git a/compiler/hsSyn/HsPat.lhs b/compiler/hsSyn/HsPat.lhs
index 84eadb7..e87a6a2 100644 (file)
--- a/compiler/hsSyn/HsPat.lhs
+++ b/compiler/hsSyn/HsPat.lhs
@@ -25,7 +25,7 @@ module HsPat (
 
        isBangHsBind, hsPatNeedsParens,
        patsAreAllCons, isConPat, isSigPat, isWildPat,
-       patsAreAllLits, isLitPat, isIrrefutableHsPat
+       patsAreAllLits, isLitPat, isIrrefutableHsPat, hasViewPat
     ) where
 
 import {-# SOURCE #-} HsExpr           (SyntaxExpr, LHsExpr, pprLExpr)
@@ -369,6 +369,34 @@ patterns are treated specially, of course.
 
 The 1.3 report defines what ``irrefutable'' and ``failure-free'' patterns are.
 \begin{code}
+hasViewPat :: LPat id -> Bool
+hasViewPat (L _ p) = go p where
+  go (WildPat _)             = False
+  go (VarPat _)              = False
+  go (VarPatOut _ _)         = False
+  go (LazyPat p)             = hasViewPat p
+  go (AsPat _ p)             = hasViewPat p
+  go (ParPat p)              = hasViewPat p
+  go (BangPat p)             = hasViewPat p
+  go (ListPat p _)           = any hasViewPat p
+  go (TuplePat p _ _)        = any hasViewPat p
+  go (PArrPat p _)           = any hasViewPat p
+  go (ConPatIn _ p)          = go' p
+  go (ConPatOut _ _ _ _ p _) = go' p
+  go (ViewPat _ _ _)         = True
+  go (QuasiQuotePat _)       = False
+  go (LitPat _)              = False
+  go (NPat _ _ _)            = False
+  go (NPlusKPat _ _ _ _)     = False
+  go (TypePat _)             = False
+  go (SigPatIn p _)          = hasViewPat p
+  go (SigPatOut p _)         = hasViewPat p
+  go (CoPat _ _ _)           = False
+  go' p = case p of
+    PrefixCon ps              -> any hasViewPat ps
+    RecCon (HsRecFields fs _) -> any (hasViewPat . hsRecFieldArg) fs
+    InfixCon p1 p2            -> hasViewPat p1 || hasViewPat p2
+
 isWildPat :: Pat id -> Bool
 isWildPat (WildPat _) = True
 isWildPat _           = False