cwality-maps: also traverse generic aeson values

this works surprisingly well, actually

cwality-maps/Substitute.hs

@@ -53,7 +53,12 @@ trivial :: t -> b -> ([a], t)
 trivial = const . ([],)
 
 instance {-# OVERLAPS #-} Substitutable A.Value where
-  substitute = trivial
+  substitute (A.Object fields) params =
+    second A.Object $ traverse (`substitute` params) fields
+  substitute (A.String str) params =
+    second A.String $ substitute str params
+  substitute other params = ([], other)
+
 
 instance Substitutable Int where
   substitute = trivial