I know we have class IsString a where fromString :: String -> a But do we have an inverse generic function toString defined anywhere? IsString implies that the type `a` is a subset of String; if all we have is fromString, then IsString defines *supersets* of String. To me, the most logical thing would be that IsString defines bijections to String (i.e. things that are subsets *and* supersets). The reason this came up is that I'm getting pretty sick of type-juggling different string types from different libraries (String, Text, various ByteStrings), especially since I have to tweak all the functions I use if a type changes; discovering fromString was fantastic, but without toString, I can't define something like reString :: (IsString a, IsString b) => a -> b which is great to have if your putStrLn only accepts one kind of string, and you have several distinct ones floating around. Thanks, Ben