(def mapnil
 " (mapnil f a) 
 Map a function over a tuple or array and return nil."
 (fn [f t]
  (var i 0)
  (def len (length t))
  (while (< i len)
    (f (get t i))
    (varset! i (+ i 1)))))

(def mapt 
 " (mapt f t)
 Map a function over a tuple or array and produce a new tuple."
 (fn [f t]
  (var i 0)
  (def len (length t))
  (def accum [])
  (while (< i len)
    (array-push accum (f (get t i)))
    (varset! i (+ i 1)))
  (apply tuple accum)))
    
(def mapa 
 " (mapa f a) 
 Map a function over a tuple or array and produce a new array."
 (fn [f t]
  (var i 0)
  (def len (length t))
  (def accum [])
  (while (< i len)
    (array-push accum (f (get t i)))
    (varset! i (+ i 1)))
  accum))