Where are the bind and identity functions on the Nullable<T> monad?

Question

My understanding of monads is still being formed. I understand that aside from being associative, the other three contracts that a monad has to adhere to are identity, pure and bind.

I infer that the constructor of Nullable<T> forms the pure function, I do not see any identity and bind functions on Nullable<T>.

Answer 1

.Net does not contain the bind method for Nullable<T>, but it gives you enough to build one yourself:

static Nullable<T2> Bind<T1, T2>(Nullable<T1> source, Func<T1, Nullable<T2>> f)
    where T1 : struct where T2 : struct
{
    return source.HasValue ? f(source.Value) : null;
}

C# does contain something similar (but less general) than bind: the null conditional operator ?.. Assuming a is of type Nullable<T1> and B is a property of type Nullable<T2>, then a?.B is equivalent to Bind(a, x => x.B).