ummels

(fn [s e]
  (let [squares   (apply str (take-while #(<= % e) (iterate #(* % %) s)))
        filler    (drop (count squares) (repeat (#(* % %) (Math/ceil (Math/sqrt (count squares)))) \*))
        elements  (concat squares filler)
        dimension (int (Math/sqrt (count elements)))
        cardinal  (- (* 2 dimension) 1)
        canvas    (vec (repeat cardinal ""))
        start-pos (* 2 (quot (dec dimension) 2))
        path      (take (count elements) (mapcat #(repeat (+ 2 (* 2 %)) (if (odd? %) dec inc)) (range)))
        balance   (fn [c] (#(apply str `(~@% ~@(interpose \  c) ~@%)) (repeat (/ (- cardinal (- (* 2 (count c)) 1)) 2) \ )))]

ummels

;; ummels's solution to Squares Squared
;; https://4clojure.com/problem/138

(fn [start end]
  (letfn
    [(squares [start end]
       (take-while #(<= % end) (iterate #(* % %) start)))
     (arrange [x]
       (let [n (count x)
             dim (int (Math/ceil (Math/sqrt n)))

ummels

/** Implicit class for adding `|>` and `tap` operations to `AnyVal`.
  * 
  * See `http://stackoverflow.com/a/11120847/839131`.
  */
implicit class PipeAndTap[A](val x: A) extends AnyVal {
  /** Applies `f` to the underlying value and returns the result. */
  def |>[B](f: A => B) = f(x)

  /** Applies `f` to the underlying value `x` (presumably with side effects)
    * and returns `x`.

ummels

object Util {
  /** Merges a collection of streams into a single stream.
    *
    * Returns a sorted stream if all input streams are sorted.
    */
  def mergeStreams[A](streams: Traversable[Stream[A]])(implicit ord: Ordering[A]): Stream[A] = {
    val streams1 = streams.toList filterNot (_.isEmpty) sortBy (_.head)
    if (streams1.isEmpty)
      Stream.empty
    else {