revised HLength

[hs-rrdtool.git] / Data / HList / String.hs

diff --git a/Data/HList/String.hs b/Data/HList/String.hs
index e3f878a25b69a8ecb82109dca957cc3c6d56c75a..6d4d52ddfeba32fbaaad0c5488027a8ce81c1bd1 100644 (file)
--- a/Data/HList/String.hs
+++ b/Data/HList/String.hs
@@ -11,11 +11,17 @@ import Types.Data.Num.Decimal.Literals.TH
 import Types.Data.Num.Ops
 
 
-class HString s
+class (Show s, Eq s) => HString s
 
 instance HString HNil
 
-instance IntegerT c => HString (HCons c s)
+instance ( Show c
+         , Show s
+         , Eq c
+         , Eq s
+         , IntegerT c
+         )
+    => HString (HCons c s)
 
 hString :: QuasiQuoter
 hString = QuasiQuoter quoteStrExp quoteStrPat