minor implementation for parser

(simple type and defn)

README.md

@@ -22,7 +22,7 @@
 
 ## Syntax Spec
 
-```spec
+```c
 program     := defn*
 
 defn        := VAL type ID ;
@@ -55,3 +55,56 @@ lambda      := param_list compound
 
 compound    := LCURLY (stmt)* expr? RCURLY
 ```
+
+### AST Spec
+
+```c
+NODE_PROGRAM:
+    token: PROGRAM
+    children: NODE_DEFN*
+
+NODE_DEFN:
+    token: VAL
+    children: NODE_TYPE, TOKEN_ID, (NODE_EXPR)?
+    children_count: 2 | 3
+
+NODE_TYPE_SIMPLE:
+    token: ID  
+    children: NODE_ID NODE_TYPE_STAR*
+    children_count: 1+
+NODE_TYPE_COMPLEX:
+    token: COMPLEX_TYPE
+    children: NODE_TYPE_PARAM NODE_TYPE_OUT
+NODE_TYPE_PARAM
+    token: TYPE_PARAM
+    children: (NODE_TYPE | NODE_TYPE_COMPLEX)*
+    children_count: 0+
+NODE_TYPE_OUT
+    token: TYPE_OUT
+    children: (NODE_TYPE | NODE_TYPE_COMPLEX)?
+
+NODE_EXPR:
+    token: EXPR
+    children: (atom)+
+// atom definition
+NODE_NUM:
+    token: NUM
+NODE_STR:
+    token: STR
+NODE_LAMBDA:
+    token: LAMBDA
+    children: NODE_PARAM_LIST NODE_COMPOUND
+NODE_COMPOUND:
+    token: COMPOUND
+    children: (NODE_STMT)* (NODE_EXPR)?
+    children_count: 0+
+    
+
+NODE_PARAM_LIST:
+    token: PARAM_LIST
+    children: NODE_PARAM*
+NODE_PARAM:
+    token: PARAM
+    children: NODE_TYPE, TOKEN_ID
+
+```