(defn slide
	"Slides a sequence by n. That is, apply f to every set of n elements of src.
	Ex: (slide \"vida\" 2) returns (\"da\" \"id\" \"vi\").
	Ex: (slide (fn [c] (reduce #(+ %1 %2) c)) '(1 2 3 4 5) 4) return ((14 10) (3 4 5))
	Ex: (slide (fn [c] (reduce #(+ %1 %2) c)) '(1 2 3 4 5) 2) return ((9 7 5 3) (5))
	Returns a list where first is the result of f applied to every slide and
	rest are the elements of src that couldn't fit in a slide of size n."
	[f src n]
	(loop [s src
		   r (empty src)]
		(let [w (take n s)]
			(if (> n (count w))
				(list r w)
				(recur  (rest s)
					(lazy-seq (cons (f w) r)))))))