OCaml error: Unbound module Event - multithreading

Question

I try to build a short ocaml event example. But when I compile, the error in the title appears.
The question of: unbound module Event error when compiling Ocaml game was not helpful for me.
The system is Kubuntu 14.04 and I installed ocaml over aptitude, so installed packages are:
camlp4, ledit, libfindlib-ocaml, libfindlib-ocaml-dev, liboasis-ocaml, liboasis-ocaml-dev, libodn-ocaml, libodn-ocaml-dev, libtype-conv-camlp4-dev, oasis, ocaml, ocaml-base, ocaml-base-nox, ocaml-compiler-libs, ocaml-doc, ocaml-findlib, ocaml-interp, ocaml-native-compilers, ocaml-nox
The OCaml compiler is version 4.01.0
Here is my short test program.
open Thread;;
open Event;;
let chan = Event.new_channel();;
let a () =
Printf.printf "A waiting...\n";;
let sigRX = Event.receive chan in
Printf.printf "A received over channel\n";
let v = Event.sync sigRx in
Printf.printf "A running\n";
Printf.printf "A done!\n";;
let b () =
Thread.delay 0.8
Printf.printf "B sending...\n";;
let sigTX = Event.send "wake up" in
Event.sync sigTX;
Printf.printf "B done!\n";;
let t_a = Thread.create a ();;
let t_b = Thread.create b ();;
I tried to compile this single file (test.ml) with:
ocamlc -thread unix.cma threads.cma test.ml
The response is:
File "test.ml", line 2, characters 0-10:
Error: Unbound module Event
I googled, found some "thread-using-tips" like: http://caml.inria.fr/pub/docs/manual-ocaml/libthreads.html#c%3Athreads
In /usr/lib/ocaml is an threads folder and an thread.mli. Inside the threads folder there are this files:
-rw-r--r-- 1 root root 487 Jan 2 2014 condition.cmi
-rw-r--r-- 1 root root 487 Jan 2 2014 condition.cmx
-rw-r--r-- 1 root root 1203 Jan 2 2014 event.cmi
-rw-r--r-- 1 root root 1867 Jan 2 2014 event.cmx
-rw-r--r-- 1 root root 421 Jan 2 2014 mutex.cmi
-rw-r--r-- 1 root root 407 Jan 2 2014 mutex.cmx
-rw-r--r-- 1 root root 1859 Jan 2 2014 thread.cmi
-rw-r--r-- 1 root root 1308 Jan 2 2014 thread.cmx
-rw-r--r-- 1 root root 62778 Jan 2 2014 threads.a
-rw-r--r-- 1 root root 47047 Jan 2 2014 threads.cma
-rw-r--r-- 1 root root 1258 Jan 2 2014 threads.cmxa
-rw-r--r-- 1 root root 4145 Jan 2 2014 threadUnix.cmi
-rw-r--r-- 1 root root 1515 Jan 2 2014 threadUnix.cmx
What am I missing? I assume, that the Event is packed in Thread Module?

Answer 1

This command line works for me to get past the unbound module problem.
$ ocamlc -I +threads -c test.ml
There are errors in your code, but I imagine you'll know how to fix them.
This full command line will probably work, but I can't be sure because of the errors:
$ ocamlc -thread -I +threads unix.cma threads.cma test.ml
(There are some higher-level tools for building OCaml programs that you might want to learn about at some point.)