generator x = Mono [1..x]
numberFilter xs = let primeList = filter @ {\underline {isPrime} $ _1 $ @ xs
                      evenList  = filter @ {\underline {even} $ _2 $ @ xs    in
                  Delta evenList (Mono primeList)
count xs = return (length xs)

numberCount x = count =<< numberFilter =<< generator x