std.concurrency : using delegate in lieu of function

[Gabriel Huau]

Hello,

I would like to know, why the module std.concurrency use function()
parameter in lieu of delegate ? 

Delegate would be usefull for example to pass Function Member to
spawn().

Example :

class Foo
{
	void test() 
	{	
		for(;;)
		{
			receive(
				(string s) { writeln("string"); }
			);
		}
	
	}
}

void main()
{
	Foo l = new Foo();
	void delegate() dg;

	dg = &l.test;
	auto a = spawn(dg);

	a.send("test");
}

I have tested and it worked.