add bitwise and modular operations.

README.md

@@ -47,7 +47,8 @@ ideally, very fast) [Shen](http://shenlanguage.org) implementation.
 The following predicates are built-in to rusty-wam.
 
 * Arithmetic support:
-    * is/2 works for (+)/2, (-)/{1,2}, (*)/2, (//)/2, (div)/2, (/)/2, (rdiv)/2.
+    * is/2 works for (+)/2, (-)/{1,2}, (*)/2, (//)/2, (div)/2, (/)/2, (rdiv)/2,
+      (xor)/2, (rem)/2, (mod)/2, (/\)/2, (\/)/2, (>>)/2, (<<)/2.
 * atomic/1
 * call/N (1 <= N <= 63)
 * catch/3