+let commandInput = argv[2];
+let commandInputTokenized = tk.tokenize(commandInput);
+console.log(commandInputTokenized);
+
+/**
+ * matchee pair of commandInputTokenized
+ */
+let commandTPair : TokenMatcheePair = {matched:[],
+ remained: commandInputTokenized};
+
+
+let tInt = m1TType(tk.TokenType.INT);
+let tFlo = m1TType(tk.TokenType.FLO);
+let tStr = m1TType(tk.TokenType.STR);
+function tBool (x : TokenMatcheePair) :tk.Maybe<TokenMatcheePair> {
+ let text = x.remained[0].text
+ if (text == "true" || text == "false"){
+ return thenDo(toSome(x), m1TType(tk.TokenType.ID));
+ }else{
+ return {_tag : "None"};
+ }
+}
+
+/**
+ * define the right hand side of a grammar
+ * eg. `LHS ::= a + b`
+ * @param process the right hand side processing : eg. `a + b` in `LHS`
+ * @param arrange define the order (0 starting) of the elements of the result.
+ * ast. : eg. `a + c` is `1 0 2` `(+ a c)`
+ * @returns the processed ast.
+ */
+function gramRHS (process: Function, arrange : number[]){
+ return (m : TokenMatcheePair)=>{
+
+ let result : tk.Maybe<TokenMatcheePair> = process(m);
+ console.log(`result ${result}`)
+ if (result._tag == "None"){
+ return result;
+ }
+ else{
+ let matched = result.value.matched;
+ let return_array : tkTree[] = Array(arrange.length);
+
+ arrange.forEach((val, index) => {
+ return_array[arrange[index]] = matched[index];
+ });
+
+ return return_array;
+ }
+ }
+}
+
+/**
+ * CONST ::= INT | STR | FLO | BOOL
+ */
+var constParser = gramRHS((x : TokenMatcheePair)=>
+ {return thenDo(toSome(x),orDo(orDo(orDo(tInt,tFlo),tStr),tBool))}, [0]);