RosettaCodeData/Task/Loops-For/J/loops-for.j

3 : 0
        for_i. 1 + i. y do.
             z =. ''

             for. 1 + i. i do.
                  z=. z,'*'
             end.

             z 1!:2 ] 2
         end.

        i.0 0
   )