Prelude> import Control.Monad.Fix
Prelude Control.Monad.Fix> let loeb = fix (fmap . flip id =<<)
<interactive>:1:16:
Ambiguous type variable `f' in the constraint:
`Functor f' arising from a use of `fmap' at <interactive>:1:16-19
Probable fix: add a type signature that fixes these type variable(s)
Prelude Control.Monad.Fix>