diff --git a/src/ast/system.myc b/src/ast/system.myc
new file mode 100644
index 0000000..c7d81a4
--- /dev/null
+++ b/src/ast/system.myc
@@ -0,0 +1,19 @@
+;; Myc System Library
+;; Standard macros and core utilities.
+
+(do
+  (macro while [cond body]
+    `((fn [] (if ~cond
+               (do ~body (again))
+             )))
+  )
+
+  ;; Creates a stateful cache (Series) from a stateless stream.
+  (macro cache [lookback type src]
+    `(do
+       (def data (series ~lookback ~type))
+       (pipe [~src] (fn [s] (do (push data s))))
+       data
+     )
+  )
+)