I wanted to run the map function from Data.Map, let's call it M.map, but inside a monad transformer stack including the Error monad.

M.map has this type:

M.map :: (Ord k) => (a -> b) -> Map k a -> Map k b

However, I want to use a mapping function that has type

(Monad m) => a -> m b

(i.e. errors could be thrown during the computation, a log could be written, etc)

I wrote the following. Any comments on this way of doing things?

mapMapM :: (Monad m, Ord k) => (a -> m b) -> Map k a -> m (Map k b)
mapMapM g mapIn = do
let h (k,a) = do
b <- g a
return (k,b)
y <- mapM h (M.toAscList mapIn)
return $ M.fromAscList y