> The author is mistaken. There are only two functions necessary for a monad: >>= and return Probably because monads are frequently described as triples -- tw

> The author is mistaken. There are only two functions necessary for a monad: >>= and return Probably because monads are frequently described as triples -- two functions and a functor. The author seems to have reduced that to three functions (presumably fmap) without realizing that it isn't sufficient.