sergey-scherbina

import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;

// Profunctor Optics
// http://programming-journal.org/2017/1/7/
public interface Optics {

    static void main(final String[] args) {
        System.out.println(Pair.<String, Optional<Pair<Integer, Boolean>>>

sergey-scherbina

import scala.xml.pull._
import scalaz._
import Scalaz._

trait Input[F[_]] {
  type =>>[A, B] = StateT[Option, F[A], B]

  def uncons[A](f: F[A]): Option[(F[A], A)]
  def next[A]: (A =>> A) = StateT { uncons }
  def none[A, B] = Option.empty[(F[A], B)]

sergey-scherbina

object Monads {

  trait Functor[F[_]] {
    def map[A, B](fa: F[A])(f: A => B): F[B]
  }

  trait Monad[M[_]] extends Functor[M] {
    self =>

    def unit[A](a: => A): M[A]