+instance toString Expr where
+ toString e = concat $ print e
+
+printSelectors :: [FieldSelector] -> [String]
+printSelectors x = case x of [] = [""]; _ = [".":printersperse "." x]
+
+printFunCall :: String [Expr] -> [String]
+printFunCall s args = [s, "(":printersperse "," args] ++ [")"]