Why can lambdas convert function calls into Actions?

Question

In this code fragment:

List<String> names = new List<String>();
names.Add("Bruce");
names.Add("Tom");
names.Add("Tim");
names.Add("Richard");

names.ForEach(x => Print(x));

private static string Print(string s)
{
    Console.WriteLine(s);
    return s;
}

Print is not an Action for sure since it is returning string; however x=> Print(x) is, why?

Answer 1

The type of the lambda expression x => Print(x) is determined based on its context. Since the compiler knows that the lambda is assigned to Action<string>, the compiler disregards the return type of the Print(s) method as if it were a statement expression.

This is a valid conversion:

Action<string> myAction = y => Print(y);

In other words, both

Print("something");

and

int x = Print("something");

are correct usages of the Print method; they can be used in lambdas in the same way.