1 files changed, 152 insertions, 0 deletions
diff --git a/src/kahn.ml b/src/kahn.ml
new file mode 100644
index 0000000..91b251f
--- /dev/null
+++ b/src/kahn.ml
@@ -0,0 +1,152 @@
+module type S = sig
+  type 'a process
+  type 'a in_port
+  type 'a out_port
+
+  val new_channel: unit -> 'a in_port * 'a out_port
+  val put: 'a -> 'a out_port -> unit process
+  val get: 'a in_port -> 'a process
+
+  val doco: unit process list -> unit process
+
+  val return: 'a -> 'a process
+  val bind: 'a process -> ('a -> 'b process) -> 'b process
+
+  val run: 'a process -> 'a
+end
+
+module Lib (K : S) = struct
+
+  let ( >>= ) x f = K.bind x f
+
+  let delay f x =
+    K.bind (K.return ()) (fun () -> K.return (f x))
+
+  let par_map f l =
+    let rec build_workers l (ports, workers) =
+      match l with
+      | [] -> (ports, workers)
+      | x :: l ->
+          let qi, qo = K.new_channel () in
+          build_workers
+            l
+            (qi :: ports,
+             ((delay f x) >>= (fun v -> K.put v qo)) :: workers)
+    in
+    let ports, workers = build_workers l ([], []) in
+    let rec collect l acc qo =
+      match l with
+      | [] -> K.put acc qo
+      | qi :: l -> (K.get qi) >>= (fun v -> collect l (v :: acc) qo)
+    in
+    let qi, qo = K.new_channel () in
+    K.run
+      ((K.doco ((collect ports [] qo) :: workers)) >>= (fun _ -> K.get qi))
+
+end
+
+
+module Th: S = struct
+  type 'a process = (unit -> 'a)
+
+  type 'a channel = { q: 'a Queue.t ; m: Mutex.t; }
+  type 'a in_port = 'a channel
+  type 'a out_port = 'a channel
+
+  let new_channel () =
+    let q = { q = Queue.create (); m = Mutex.create (); } in
+    q, q
+
+  let put v c () =
+    Mutex.lock c.m;
+    Queue.push v c.q;
+    Mutex.unlock c.m;
+    Thread.yield ()
+
+  let rec get c () =
+    try
+      Mutex.lock c.m;
+      let v = Queue.pop c.q in
+      Mutex.unlock c.m;
+      v
+    with Queue.Empty ->
+      Mutex.unlock c.m;
+      Thread.yield ();
+      get c ()
+
+  let doco l () =
+    let ths = List.map (fun f -> Thread.create f ()) l in
+    List.iter (fun th -> Thread.join th) ths
+
+  let return v = (fun () -> v)
+
+  let bind e e' () =
+    let v = e () in
+    Thread.yield ();
+    e' v ()
+
+  let run e = e ()
+end
+
+module Seq: S = struct
+  type 'a process = (('a -> unit) option) -> unit
+
+  type 'a channel = 'a Queue.t
+  type 'a in_port = 'a channel
+  type 'a out_port = 'a channel
+
+  type task = unit -> unit
+
+  let tasks = Queue.create ()
+
+  let new_channel () =
+    let q = Queue.create () in
+    q, q
+
+  let put x c =
+    fun cont ->
+      Queue.push x c;
+      match cont with
+      | None -> ()
+      | Some cont ->  Queue.push cont tasks
+
+  let rec get c =
+    fun cont ->
+      try
+        let v = Queue.pop c in
+        match cont with
+        | None -> ()
+        | Some cont -> Queue.push (fun () -> cont v) tasks
+      with Queue.Empty ->
+        Queue.push (fun () -> get c cont) tasks
+
+  let doco l =
+    fun cont ->
+      List.iter (fun proc -> Queue.push (fun () -> proc None) tasks) l;
+      match cont with
+      | None -> ()
+      | Some cont -> Queue.push cont tasks
+
+  let return v =
+    fun cont ->
+      match cont with
+      | None -> ()
+      | Some cont -> Queue.push (fun () -> cont v) tasks
+
+  let bind e f =
+    fun cont ->
+      Queue.push (fun () -> e (Some (fun r -> f r cont))) tasks
+    
+  let run e =
+    let ret = ref None in
+    e (Some (fun v -> ret := Some v));
+    while not (Queue.is_empty tasks) do
+      let task = Queue.pop tasks in
+      task ()
+    done;
+    match !ret with
+    | Some k -> k
+    | None -> assert false
+
+end
+