From 81b6e0d7038a99c66456033c8285f740a3b0c719 Mon Sep 17 00:00:00 2001
From: Eduardo Julian
Date: Thu, 18 Aug 2022 21:34:21 -0400
Subject: Added support for Communicating Sequential Processes (CSP).

---
 .../source/library/lux/control/concurrency/cps.lux | 76 ++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 stdlib/source/library/lux/control/concurrency/cps.lux

(limited to 'stdlib/source/library')

diff --git a/stdlib/source/library/lux/control/concurrency/cps.lux b/stdlib/source/library/lux/control/concurrency/cps.lux
new file mode 100644
index 000000000..f8cd41a77
--- /dev/null
+++ b/stdlib/source/library/lux/control/concurrency/cps.lux
@@ -0,0 +1,76 @@
+(.require
+ [library
+  [lux (.except try)
+   [abstract
+    [functor (.only Functor)]
+    [monad (.only Monad do)]]
+   [control
+    ["[0]" try (.only Try) (.use "[1]#[0]" monad)]
+    ["[0]" exception (.only Exception)]]]]
+ [//
+  ["[0]" async (.only Async) (.use "[1]#[0]" monad)]
+  ["[0]" frp]])
+
+(type .public (Process a)
+  (Async (Try a)))
+
+(type .public Channel' frp.Channel')
+(type .public Channel frp.Channel)
+(type .public Sink frp.Sink)
+
+(def .public channel
+  (All (_ a) (-> Any [(Channel a) (Sink a)]))
+  frp.channel)
+
+(def .public functor
+  (Functor Process)
+  (implementation
+   (def (each $)
+     (async#each (try#each $)))))
+
+(def .public monad
+  (Monad Process)
+  (implementation
+   (def functor ..functor)
+   (def in (|>> try#in async#in))
+   (def (conjoint atatx)
+     (do async.monad
+       [tatx atatx]
+       (when tatx
+         {try.#Success atx}
+         atx
+         
+         {try.#Failure error}
+         (in {try.#Failure error}))))))
+
+(exception.def .public channel_has_been_closed)
+
+(def .public (read it)
+  (All (_ r w)
+    (-> (Channel' r w) (Process [r (Channel' r w)])))
+  (let [[output resolver] (async.async [])]
+    (exec
+      (async.future
+       (async.upon! (function (_ head,tail)
+                      (resolver (when head,tail
+                                  {.#Some [head tail]}
+                                  {try.#Success [head tail]}
+                                  
+                                  {.#None}
+                                  (exception.except ..channel_has_been_closed []))))
+                    it))
+      output)))
+
+(def .public (write value sink)
+  (All (_ w)
+    (-> w (Sink w) (Process Any)))
+  (async.future (at sink feed value)))
+
+(def .public (close sink)
+  (All (_ w)
+    (-> (Sink w) (Process Any)))
+  (async.future (at sink close)))
+
+(def .public try
+  (All (_ a) (-> (Process a) (Process (Try a))))
+  (async#each (|>> {try.#Success})))
-- 
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