What is this type A in learning Scalaz for the sum function?

Question

In Learning Scalaz there is a type parameter on the method sum.

Does this mean that the type A is of type Monoid? However that seems wrong, if the type A is a Monoid then how can it also be an integer as it is used in the example. I must be reading the type parameter wrong.

What is the meaning of the type parameter? How should I be reading it?

def sum[A: Monoid](xs: List[A]): A = {
     val m = implicitly[Monoid[A]]
     xs.foldLeft(m.mzero)(m.mappend)
   }

Answer 1

A: Monoid is a type parameter with a Context Bound. It's syntactic sugar.

The following:

def sum[A: Monoid](xs: List[A]): A

gets desugared into:

def sum[A](xs: List[A])(implicit val $ev: Monoid[A]): A