docs: hold blocks in LEARN.md (36-hold), spec 5.16, ACTOR.md; TODO: m:n scheduler and follow-ups

2 files changed, 25 insertions, 0 deletions

diff --git a/examples/learn/36-hold.out b/examples/learn/36-hold.out
new file mode 100644
index 0000000..8bd1af1
--- /dev/null
+++ b/examples/learn/36-hold.out
@@ -0,0 +1 @@
+2000
diff --git a/examples/learn/36-hold.zc b/examples/learn/36-hold.zc
new file mode 100644
index 0000000..6052129
--- /dev/null
+++ b/examples/learn/36-hold.zc
@@ -0,0 +1,24 @@
+namespace;
+include rt, actor;
+typecheck on;
+
+// one counter for every actor. only the functions written in the block can touch it,
+// and each call holds the block's lock, so a read and the write after it can't interleave.
+hold {
+	shared let hits = 0;
+	fn hit() { let seen = hits; hits = seen + 1; return seen; }
+	fn total() { return hits; }
+}
+
+int work(int n) { let i = 0; while (i < n) { hit(); i++; } return n; }
+
+fn main() {
+	actor.Actor<int,int>* a = rt.new(actor.Actor<int,int>), b = rt.new(actor.Actor<int,int>);
+	a.spawn(work); b.spawn(work);
+	a.send(1000); b.send(1000);
+	a.recv(fn(int n) { return 0; }); b.recv(fn(int n) { return 0; });
+	a.await(); b.await();
+	rt.put_n(total()); rt.put_c(10);
+	a.close(); b.close();
+	return 0;
+}