1 files changed, 24 insertions, 0 deletions
diff --git a/stdlib/source/lux/data/env.lux b/stdlib/source/lux/data/env.lux
new file mode 100644
index 000000000..7c29f5833
--- /dev/null
+++ b/stdlib/source/lux/data/env.lux
@@ -0,0 +1,24 @@
+(;module:
+  lux
+  (lux (control functor
+                comonad)))
+
+(type: #export (Env e a)
+  {#env e
+   #value a})
+
+(struct: #export Functor<Env> (All [e] (Functor (Env e)))
+  (def: (map f fa)
+    (update@ #value f fa)))
+
+(struct: #export CoMonad<Env> (All [e] (CoMonad (Env e)))
+  (def: functor Functor<Env>)
+
+  (def: unwrap (get@ #value))
+
+  (def: (split wa)
+    (set@ #value wa wa)))
+
+(def: #export (local change env)
+  (All [e a] (-> (-> e e) (Env e a) (Env e a)))
+  (update@ #env change env))