fronx-4clojure-solution85.clj

;; fronx's solution to Power Set
;; https://4clojure.com/problem/85

(fn [s]
  (let [bit-filter (fn [items mask]
                     (set
                       (keep-indexed
                         (fn [idx item]
                            (if (bit-test mask idx)
                                item))
                          items)))]
    (set (for [mask (range 0 (Math/pow 2 (count s)))]
            (bit-filter s mask)))))