Hi I have two functions, foldrEntries and foldrEntriesW, where the latter is a WriterT version of the former. Here are the type signatures: foldrEntries :: (Entry -> a -> a) -> a -> (String -> a) -> Entries -> a foldrEntriesW :: (Monoid w, Monad m) => (Entry -> a -> WriterT w m a) -> WriterT w m a -> (String -> WriterT w m a) -> Entries -> WriterT w m a I want to implement foldrEntries in terms of foldrEntriesW using the Identity monad and ignore/not use the writer result. I am doing this in order to reuse the foldrEntriesW implementation and avoid code duplication. This is what I have so far: http://lpaste.net/145641 But the compiler complains about ambiguous type for the writer reult I am ignoring (message in the above lpaste). Normally I think the way around this is to provide explicit type annotation for "foldIt", but in this case the result type depends on the type of "a" in foldrEntries type and I don't know how to express this and make the compiler happy. (I was able to make it work by calling "tell ()", basically writing a dummy value, which lets compiler know what the type is, but this is not so good - I don't want to make artificial function calls like this.) Can anybody help me with that? Many Thanks Martin