Thread communication

[Alex Parrill via Digitalmars-d-learn]

On Wednesday, 5 August 2015 at 14:31:20 UTC, Marc Schütz wrote:
> Maybe we can lift this restriction if we know that the thread's 
> main function is pure and takes no references to mutable data, 
> because then it can by definition never mess up the program's 
> state.

That'd be a pretty useless thread; how would it communicate 
results back to the main thread (or wherever it should go)?