std.concurrency msg passing

[cal]

On Thursday, 18 October 2012 at 18:31:09 UTC, Sean Kelly wrote:
> On Oct 17, 2012, at 11:29 PM, Joshua Niehus
>> void foo(Tid tid) {
>>    send(tid, true);
>> }
/* snip */
> spawn() shouldn't allow you to spawn a delegate.  Last I 
> checked (which was admittedly a while ago), there were some 
> compiler issues around actually verifying the function 
> signature sent to spawn() though.

Why is foo a delegate here?