Here is a basic co-operative scheduler based version of go!(F)  that uses a channel to keep things simple, its co-op so Fiber.yield has to be called at some point. If the channel detects its in a Fiber it calls yield if there is nothing available in it:

void go(alias F)() {
    scheduler._ = new Fiber(F);
}

shared chan!Fiber scheduler; // channel contains Fibers waiting for their time slice
static this () {
    if (scheduler is null) {   
        scheduler = makeChan!Fiber(100);

        // create the workers
        auto goprocs = environment.get("GOPROCS");
        int num_threads = 1;
        if (goprocs != null) {
            num_threads = to!int(goprocs);
        }
        foreach (i; 0..num_threads) {
            // create threads that process the live fibers
            auto t = new Thread(() {
                for (;;) {
                    auto fiber = scheduler._;
                    fiber.call();
                    if (fiber.state != Fiber.State.TERM) {
                        scheduler._ (fiber);
                    }
                }
                });
            t.start();
        }
       
    }
}