- Added context/config variables, and their parsers (a.k.a. properties).

- Added a way to obtain a program's environment variables.

2 files changed, 81 insertions, 0 deletions

diff --git a/stdlib/source/lux/data/format/context.lux b/stdlib/source/lux/data/format/context.lux
new file mode 100644
index 000000000..a515052c6
--- /dev/null
+++ b/stdlib/source/lux/data/format/context.lux
@@ -0,0 +1,34 @@
+(;module:
+  lux
+  (lux (control ["p" parser]
+                ["ex" exception #+ exception:]
+                [monad #+ do])
+       (data ["R" result]
+             (coll ["d" dict]))))
+
+(exception: #export Unknown-Property)
+
+(type: #export Context
+  (d;Dict Text Text))
+
+(type: #export (Property a)
+  (p;Parser Context a))
+
+(def: #export (property name)
+  (-> Text (Property Text))
+  (function [context]
+    (case (d;get name context)
+      (#;Some value)
+      (ex;return [context value])
+      
+      #;None
+      (ex;throw Unknown-Property name))))
+
+(def: #export (run context property)
+  (All [a] (-> Context (Property a) (R;Result a)))
+  (case (property context)
+    (#R;Success [_ output])
+    (#R;Success output)
+
+    (#R;Error error)
+    (#R;Error error)))
diff --git a/stdlib/source/lux/world/env.jvm.lux b/stdlib/source/lux/world/env.jvm.lux
new file mode 100644
index 000000000..29266cc84
--- /dev/null
+++ b/stdlib/source/lux/world/env.jvm.lux
@@ -0,0 +1,47 @@
+(;module:
+  lux
+  (lux (data [text]
+             (format [context #+ Context])
+             (coll [list "L/" Functor<List>]
+                   ["d" dict]))
+       [io #- run]
+       [host #+ jvm-import]))
+
+(jvm-import java.lang.String)
+
+(jvm-import (java.util.Map$Entry k v)
+  (getKey [] k)
+  (getValue [] v))
+
+(jvm-import (java.util.Iterator a)
+  (hasNext [] boolean)
+  (next [] a))
+
+(jvm-import (java.util.Set a)
+  (iterator [] (Iterator a)))
+
+(jvm-import (java.util.Map k v)
+  (entrySet [] (Set (Map$Entry k v))))
+
+(jvm-import java.lang.System
+  (#static getenv [] (java.util.Map String String)))
+
+(def: (consume-iterator f iterator)
+  (All [a b] (-> (-> a b) (Iterator a) (List b)))
+  (if (Iterator.hasNext [] iterator)
+    (#;Cons (f (Iterator.next [] iterator))
+            (consume-iterator f iterator))
+    #;Nil))
+
+(def: (entry-to-kv entry)
+  (All [k v] (-> (Map$Entry k v) [k v]))
+  [(Map$Entry.getKey [] entry)
+   (Map$Entry.getValue [] entry)])
+
+(def: #export read
+  (IO Context)
+  (io (|> (System.getenv [])
+          (Map.entrySet [])
+          (Set.iterator [])
+          (consume-iterator entry-to-kv)
+          (d;from-list text;Hash<Text>))))