(module main ()

  (import
    (scheme)
    (chicken format)
    (prefix (arith num) n:) 
    (prefix (arith str) s:)
    (prefix (arith mix) m:))

  (printf "num add: ~a, sub: ~a~%" (n:add 3 4) (n:sub 3 4)) 
  (printf "str add: ~a, sub: ~a~%" (s:add "3" "4") (s:sub "3" "4")) 
  (printf "mix add: ~a, sub: ~a~%" (m:add 3 4) (m:sub "3" "4")) 
  )