Different methods of implementing a specific parsing rule for a compiler

Let's say we have a rule in parsing tokens that specifies:

x -> [y[,y]*]

Where the brackets '[ ]' mean that anything in them is optional in order for the rule to take place and the * means 0 or more. e.g it could be:

x : (empty) 
  OR
x : y 
  OR
x : y,y

as well etc. (the above are examples of input that 'x' rule would be activated, not how the code should be)

I have tried the following that works already

x : y commaY
  |
  ;

commaY : COMMA y commaY
       |
       ;

I would like to know alternative options in the above that would make it work, if there are any, for educational purposes.

Thank you in advance.

Solution

EDIT my earlier answer was incorrect (as pointed out in the comments), but I cannot remove an accepted answer, so I decided to edit it.

You will need (at least) 2 rules for x -> [y[,y]*]. Here is another possibility:

x
 : list
 | /* eps */
 ;

list
 : list ',' y
 | y
 ;