From 9671484b6cb3f3c56d6a3053a4a55b4634c14a89 Mon Sep 17 00:00:00 2001
From: Eduardo Julian
Date: Mon, 22 Aug 2022 20:45:33 -0400
Subject: Added support for the agent model.

---
 .../library/lux/control/concurrency/actor.lux      | 54 +++++++++++++++++++---
 .../library/lux/control/concurrency/agent.lux      | 25 ++++++++++
 2 files changed, 72 insertions(+), 7 deletions(-)
 create mode 100644 stdlib/source/library/lux/control/concurrency/agent.lux

(limited to 'stdlib/source/library')

diff --git a/stdlib/source/library/lux/control/concurrency/actor.lux b/stdlib/source/library/lux/control/concurrency/actor.lux
index d4c50b896..7b430da17 100644
--- a/stdlib/source/library/lux/control/concurrency/actor.lux
+++ b/stdlib/source/library/lux/control/concurrency/actor.lux
@@ -7,7 +7,9 @@
     ["[0]" pipe]
     ["[0]" try (.only Try)]
     ["[0]" exception]
-    ["[0]" io (.only IO io)]]
+    ["[0]" io (.only IO io)]
+    [function
+     [predicate (.only Predicate)]]]
    [data
     ["[0]" bit]
     ["[0]" product]]
@@ -18,7 +20,7 @@
      [primitive (.only primitive representation abstraction)]]]]]
  [//
   ["[0]" atom (.only Atom atom)]
-  ["[0]" async (.only Async Resolver)]
+  ["[0]" async (.only Async Resolver) (.use "[1]#[0]" monad)]
   ["[0]" frp (.only Channel Channel')]])
 
 (exception.def .public poisoned)
@@ -79,10 +81,11 @@
                                    (when ?state'
                                      {try.#Failure error}
                                      (let [[_ resolve] (the #obituary (representation self))]
-                                       (exec (io.run!
-                                              (do io.monad
-                                                [pending (..pending tail)]
-                                                (resolve [error state {.#Item head pending}])))
+                                       (exec
+                                         (io.run!
+                                          (do io.monad
+                                            [pending (..pending tail)]
+                                            (resolve [error state {.#Item head pending}])))
                                          (in [])))
 
                                      {try.#Success state'}
@@ -170,7 +173,7 @@
                (do async.monad
                  [outcome (async.future (..mail! mail actor))]
                  (when outcome
-                   {try.#Success}
+                   {try.#Success _}
                    async
                    
                    {try.#Failure error}
@@ -209,3 +212,40 @@
                               (at ! each try.maybe))
                           (in {.#None}))))
                     channel)))
+
+... The following behavior and messages allow Lux's actors to behave like Clojure's agents.
+... https://clojure.org/reference/agents
+
+(exception.def .public invalid)
+
+(def .public (validated ? it)
+  (All (_ state)
+    (-> (Predicate state) (Behavior state)
+        (Behavior state)))
+  (function (_ mail before actor)
+    (do (try.with async.monad)
+      [after (mail before actor)]
+      (if (? after)
+        (in after)
+        (async#in (exception.except ..invalid []))))))
+
+(def .public state
+  (All (_ state)
+    (Message state state))
+  (function (_ state self)
+    (async#in {try.#Success [state state]})))
+
+(def .public (update $)
+  (All (_ state)
+    (-> (-> state state)
+        (Message state [state state])))
+  (function (_ before self)
+    (let [after ($ before)]
+      (async#in {try.#Success [after [before after]]}))))
+
+(def .public (reset after)
+  (All (_ state)
+    (-> state
+        (Message state state)))
+  (function (_ before self)
+    (async#in {try.#Success [after before]})))
diff --git a/stdlib/source/library/lux/control/concurrency/agent.lux b/stdlib/source/library/lux/control/concurrency/agent.lux
new file mode 100644
index 000000000..bf9608cb7
--- /dev/null
+++ b/stdlib/source/library/lux/control/concurrency/agent.lux
@@ -0,0 +1,25 @@
+(.require
+ [library
+  [lux (.except)
+   [control
+    ["[0]" try (.only Try)]
+    ["[0]" io (.only IO)]]]]
+ [//
+  ["[0]" async (.only Async)]
+  ["[0]" actor (.only Actor)]
+  ["[0]" frp (.only Channel')]])
+
+(def .public Agent
+  Actor)
+
+(def .public (react! events handler agent)
+  (All (_ eventR eventW state)
+    (-> (Channel' eventR eventW)
+        (-> eventR state (Async (Try state)))
+        (Agent state)
+        (IO Any)))
+  (frp.subscribe! (function (_ event)
+                    (actor.mail! (function (_ state self)
+                                   (handler event state))
+                                 agent))
+                  events))
-- 
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