Index: library/mongodb/nx-mongo.tcl
===================================================================
diff -u -r4028b984af21ce2b0232ed8cb46572dc8336c76b -r788f2f577d21a28e0d6a05ca87562a507d929527
--- library/mongodb/nx-mongo.tcl	(.../nx-mongo.tcl)	(revision 4028b984af21ce2b0232ed8cb46572dc8336c76b)
+++ library/mongodb/nx-mongo.tcl	(.../nx-mongo.tcl)	(revision 788f2f577d21a28e0d6a05ca87562a507d929527)
@@ -454,6 +454,11 @@
 	  "in" - "all" {
 	    lappend bson $att document [list [:get relop $op] {*}[$slot bson encode -array $value]]
 	  }
+          "~" {
+            # value should be a two-element list contain pattern and options
+	    lappend bson $att document [list {$regex} regex $value]
+	  }
+
 	  default {return -code error "unknown operator $op"}
 	}
       }