add "<<" and ">>" op

Author: yjhmelody

demo

@@ -26,3 +26,4 @@ println(car(cdr(cdr(cdr(cdr(x))))));  # 5
 code = fs-readFileSync("./demo");
 println(code);
 println(os-arch());
+println((1 << 1) == 2);

src/Environment.js

@@ -113,7 +113,6 @@ Environment.prototype.evaluate = evaluate
 // let { type: "let", vars: [ VARS... ], body: AST }
 
 /**
- * 
  * 
  * @param {Object} expr 
  * @param {Environment} env 
@@ -188,8 +187,9 @@ function evaluate(expr, env) {
     }
 }
 
+// check* functions are used to check the value type 
+
 /**
- * 
  * 
  * @param {any} x 
  * @param {String} type 
@@ -203,7 +203,6 @@ function checkType(x, type) {
 }
 
 /**
- * 
  * 
  * @param {any} x 
  * @returns {any} x
@@ -213,7 +212,6 @@ function checkNumber(x) {
 }
 
 /**
- * 
  * 
  * @param {any} x 
  * @returns {any} x 
@@ -226,11 +224,10 @@ function checkDiv(x) {
 }
 
 /**
- * 
  * 
  * @param {String} op 
  * @param {any} a 
- * @param {any} b 
+ * @param {any} b
  * @returns {any} operation result
  */
 function applyOP(op, a, b) {
@@ -257,6 +254,10 @@ function applyOP(op, a, b) {
             return checkNumber(a) <= checkNumber(b)
         case '>=':
             return checkNumber(a) >= checkNumber(b)
+        case '<<':
+            return checkNumber(a) << checkNumber(b)
+        case '>>':
+            return checkNumber(a) >> checkNumber(b)
         case '==':
             return a === b
         case '!=':

src/parser.js

@@ -29,6 +29,8 @@ let PRECEDENCE = {
     ">=": 7,
     "==": 7,
     "!=": 7,
+    "<<": 8,
+    ">>": 8,
     "+": 10,
     "-": 10,
     "*": 20,
@@ -60,7 +62,7 @@ function parser(input) {
     }
 
     function skipPunc(str) {
-        // bug: cannot Identity `;`
+        // !bug: cannot Identity `;`
         if (isPunc(str)) {
             input.next()
         } else {