public static <A> List<A> flatten(List<List<A>> list) { return foldRight(list, List.<A>list(), x -> y -> concat(x, y)); }
public static <A, B> Result<List<B>> traverse(List<A> list, Function<A, Result<B>> f) { return list.foldRight( Result.success(List.list()), x -> y -> Result.map2(f.apply(x), y, a -> b -> b.cons(a))); }
private <B> TailCall<B> foldLeft_(B acc, List<A> list, Function<B, Function<A, B>> f) { return list.isEmpty() ? ret(acc) : sus(() -> foldLeft_(f.apply(acc).apply(list.head()), list.tail(), f)); }
public static <A, B> B foldRight(List<A> list, B n, Function<A, Function<B, B>> f) { return list.foldRight(n, f); }
private TailCall<List<A>> reverse_(List<A> acc, List<A> list) { return list.isEmpty() ? ret(acc) : sus(() -> reverse_(new Cons<>(list.head(), acc), list.tail())); }
private TailCall<List<A>> dropWhile_(List<A> list, Function<A, Boolean> f) { return !list.isEmpty() && f.apply(list.head()) ? sus(() -> dropWhile_(list.tail(), f)) : ret(list); }
private TailCall<List<A>> drop_(List<A> list, int n) { return n <= 0 || list.isEmpty() ? ret(list) : sus(() -> drop_(list.tail(), n - 1)); }
private TailCall<StringBuilder> toString(StringBuilder acc, List<A> list) { return list.isEmpty() ? ret(acc) : sus(() -> toString(acc.append(list.head()).append(", "), list.tail())); }
private Cons(A head, List<A> tail) { this.head = head; this.tail = tail; this.length = tail.length() + 1; }