examples/: Add programs to test fork policies

rt/examples/naive_fibonacci_fork_bundle.cpp

+#include <typon/typon.hpp>
+#include <cstdio>
+
+
+using namespace typon;
+using namespace typon::policy;
+
+Join<int> fibo(int n) {
+  if (n < 2) {
+    co_return n;
+  }
+  Forked a = co_await fork<Bundle>(fibo(n - 1));
+  Forked b = co_await fork<Bundle>(fibo(n - 2));
+  co_await Sync();
+  co_return a.get() + b.get();
+}
+
+Root root() {
+  int result = co_await fibo(40);
+  printf("%d\n", result);
+}
+
+int main() {
+  root().call();
+  puts("done");
+  return 0;
+}

rt/examples/naive_fibonacci_fork_drop.cpp

+#include <typon/typon.hpp>
+#include <cstdio>
+
+
+using namespace typon;
+using namespace typon::policy;
+
+Join<int> fibo(int n, int & result) {
+  if (n < 2) {
+    result = n;
+    co_return n;
+  }
+  // Danger !
+  // The memory for a and b could be freed before the forks complete
+  int a; co_await fork<Drop>(fibo(n - 1, a));
+  int b; co_await fork<Drop>(fibo(n - 2, b));
+  // This sync() ensures that the forks complete before a and b are freed
+  // As long as there are no exceptions...
+  co_await Sync();
+  result = a + b;
+}
+
+Root root() {
+  int result; co_await fibo(40, result);
+  printf("%d\n", result);
+}
+
+int main() {
+  root().call();
+  puts("done");
+  return 0;
+}

rt/examples/naive_fibonacci_fork_refcnt.cpp

+#include <typon/typon.hpp>
+#include <cstdio>
+
+
+using namespace typon;
+using namespace typon::policy;
+
+Join<int> fibo(int n) {
+  if (n < 2) {
+    co_return n;
+  }
+  Forked a = co_await fork<Refcnt>(fibo(n - 1));
+  Forked b = co_await fork<Refcnt>(fibo(n - 2));
+  co_await Sync();
+  co_return a.get() + b.get();
+}
+
+Root root() {
+  int result = co_await fibo(40);
+  printf("%d\n", result);
+}
+
+int main() {
+  root().call();
+  puts("done");
+  return 0;
+}

rt/examples/naive_fibonacci_fork_void.cpp

+#include <typon/typon.hpp>
+#include <cstdio>
+
+
+using namespace typon;
+
+Join<void> fibo(int n, int & result) {
+  if (n < 2) {
+    result = n;
+    co_return;
+  }
+  // Danger !
+  // The memory for a and b could be freed before the forks complete
+  int a; co_await fork(fibo(n - 1, a));
+  int b; co_await fork(fibo(n - 2, b));
+  // This sync() ensures that the forks complete before a and b are freed
+  // As long as there are no exceptions...
+  co_await Sync();
+  result = a + b;
+}
+
+Root root() {
+  int result; co_await fibo(40, result);
+  printf("%d\n", result);
+}
+
+int main() {
+  root().call();
+  puts("done");
+  return 0;
+}