1 files changed, 35 insertions, 0 deletions
diff --git a/source/lux/data/state.lux b/source/lux/data/state.lux
new file mode 100644
index 000000000..bc9858a29
--- /dev/null
+++ b/source/lux/data/state.lux
@@ -0,0 +1,35 @@
+##   Copyright (c) Eduardo Julian. All rights reserved.
+##   The use and distribution terms for this software are covered by the
+##   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+##   which can be found in the file epl-v10.html at the root of this distribution.
+##   By using this software in any fashion, you are agreeing to be bound by
+##   the terms of this license.
+##   You must not remove this notice, or any other, from this software.
+
+(;import lux
+         (lux/control (functor #as F #refer #all)
+                      (monad #as M #refer #all)))
+
+## [Types]
+(deftype #export (State s a)
+  (-> s (, s a)))
+
+## [Structures]
+(defstruct #export State/Functor (Functor State)
+  (def (F;map f ma)
+    (lambda [state]
+      (let [[state' a] (ma state)]
+        [state' (f a)]))))
+
+(defstruct #export State/Monad (All [s]
+                                 (Monad (State s)))
+  (def M;_functor State/Functor)
+
+  (def (M;wrap x)
+    (lambda [state]
+      [state x]))
+
+  (def (M;join mma)
+    (lambda [state]
+      (let [[state' ma] (mma state)]
+        (ma state')))))