fix some specs and add for parse

README.md

@@ -26,10 +26,13 @@
 
 ```
 program     := defn*
+
 defn        := VAL type ID ;
              | VAL type ID expr ;
-             
-expr        := atom atom* ;
+
+type        := ID | [] | [type] | [ type* ARROW type? ]
+
+expr        := atom atom*
 
 atom        := ID
              | NUM
@@ -40,10 +43,9 @@ atom        := ID
              | dereference
 
 stmt        := defn
-             | expr 
-             
-
-stmt        := defn | st
-
-
+             | expr ;        // expr statement
+             | return expr ; // return statement
+             | $ ID expr ;   // assignment statement
+             | if expr compound ;               // if statement
+             | if expr compound else compound ; // if-else statement
 ```