Contravariant

abstract def contramap[A, B](fa: F[A])(f: (B) ⇒ A): F[B]

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

def compose[G[_]](implicit arg0: Contravariant[G]): Functor[[α]F[G[α]]]

def compose[G[_]](implicit arg0: Invariant[G]): Invariant[[α]F[G[α]]]

def composeContravariant[G[_]](implicit arg0: Contravariant[G]): Invariant[[α]F[G[α]]]

def composeFunctor[G[_]](implicit arg0: Functor[G]): Contravariant[[α]F[G[α]]]

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

def imap[A, B](fa: F[A])(f: (A) ⇒ B)(fi: (B) ⇒ A): F[B]

Transform an F[A] into an F[B] by providing a transformation from A to B and one from B to A.

scala> import cats.implicits._
scala> import scala.concurrent.duration._
scala> val durSemigroup: Semigroup[FiniteDuration] =
     | Invariant[Semigroup].imap(Semigroup[Long])(Duration.fromNanos)(_.toNanos)
scala> durSemigroup.combine(2.seconds, 3.seconds)
res1: FiniteDuration = 5 seconds

final def isInstanceOf[T0]: Boolean

def liftContravariant[A, B](f: (A) ⇒ B): (F[B]) ⇒ F[A]

def narrow[A, B <: A](fa: F[A]): F[B]

Lifts natural subtyping contravariance of contravariant Functors.

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit