RosettaCodeData/Task/Loops-Increment-loop-index-within-loop-body/J/loops-increment-loop-index-within-loop-body-4.j

loop =: verb define@:x:
 i =. y
 while. y >: # i do.
  i =. (, (isPrime # _1 2&p.)@:{:) i
  i =. _1 (>:@:{)`[`]} i
 end.
 }: i
)