gll-abs.scala

implicit object ParserApplicative extends Applicative[Parser] {
  def point[A](a: A): Parser[A] = "" ^^^ a
  
  def ap[A, B](left: => Parser[A])(right: => Parser[A => B]): Parser[B] =
    left ~ right ^^ { (a, f) => f(a) }
}

implicit def parserSemigroup[A]: Semigroup[Parser[A]] = new Semigroup[Parser[A]] {
  def append(left: Parser[A], right: => Parser[A]): Parser[A] = left | right
}