diff --git a/README.md b/README.md
index b942f64..4027b26 100644
--- a/README.md
+++ b/README.md
@@ -42,9 +42,9 @@ atom        := ID
              | STAR
              | ANDREF
 
-stmt        := defn
-             | expr ;        // expr statement
-             | return expr ; // return statement
+stmt        := defn               // defn statement
+             | expr ;             // expr statement
+             | return expr ;      // return statement
              | DOLLAR ID expr ;   // assignment statement
              | if expr compound ;               // if statement
              | if expr compound else compound ; // if-else statement
@@ -55,3 +55,47 @@ lambda      := param_list compound
 
 compound    := LCURLY (stmt)* expr? RCURLY
 ```
+
+
+## AST Node Spec
+
+```c
+NODE_PROGRAM:
+    token: PROGRAM
+    children: NODE_DEFN*
+NODE_DEFN:
+    token: VAL
+    children: NODE_TYPE, ID, NODE_EXPR?
+NODE_TYPE:
+    token: ID | COMPLEX_TYPE
+    children: NODE_TYPE, NODE_TYPE
+            | NODE_TYPE
+NODE_EXPR:
+    token: EXPR
+    children: NODE_ATOM*
+
+// ATOM
+NODE_NUM:
+    token: NUM
+    children: none
+NODE_ID:
+    token: ID
+    children: none
+NODE_STR:
+    token: STR
+    children: none
+NODE_LAMBDA:
+    token: LAMBDA
+    children: NODE_PARAM_LIST, NODE_COMPOUND
+NODE_PARAM_LIST:
+    token: PARAM_LIST
+    children: (NODE_PARAM)*
+NODE_PARAM:
+    token: PARAM
+    children: NODE_TYPE, ID
+NODE_COMPOUND:
+    token: COMPOUND
+    children: NODE_STMT*, NODE_EXPR?
+
+
+```
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