dekellum

(ns powerset.core-test
  (:use (clojure set test)))

(defn powerset [s]
  (apply union
         #{s} ;the complete set of all s
         (map (fn [i] (powerset (disj s i))) s)))

(deftest test-powerset
  (is (= #{#{}}

aruld

//based on code from http://www.arcfn.com/2009/03/y-combinator-in-arc-and-java.html and the generic version https://gist.github.com/2571928

class YFact {
  // T function returning a T
  // T -> T
  public static interface Func<T> {
    T apply(T n);
  }

  // Higher-order function returning a T function