correctly distinguish between fun and data judgements

src/runtime/haskell/tests/basic_cnc.gf

@@ -0,0 +1,19 @@
+concrete basic_cnc of basic = open Prelude in {
+
+lincat N = {s : Str; is_zero : Bool} ;
+lincat S = Str ;
+
+lin z = {s="0"; is_zero=True} ;
+    s n = {
+      s = case n.is_zero of {
+            True  => "1" ;
+            False => n.s ++ "+" ++ "1"
+          } ;
+      is_zero = False
+    } ;
+
+lin c n = n.s ;
+
+lincat P = {};
+
+}