BinestedBitraverse

Collapse the structure by mapping each element to an element of a type that has a cats.Monoid

Invert the structure from F[G[A], G[B]] to G[F[A, B]].

Example:

scala> import cats.implicits._

scala> val rightSome: Either[Option[String], Option[Int]] = Either.right(Some(3))
scala> rightSome.bisequence
res0: Option[Either[String, Int]] = Some(Right(3))

scala> val rightNone: Either[Option[String], Option[Int]] = Either.right(None)
scala> rightNone.bisequence
res1: Option[Either[String, Int]] = None

scala> val leftSome: Either[Option[String], Option[Int]] = Either.left(Some("foo"))
scala> leftSome.bisequence
res2: Option[Either[String, Int]] = Some(Left(foo))

scala> val leftNone: Either[Option[String], Option[Int]] = Either.left(None)
scala> leftNone.bisequence
res3: Option[Either[String, Int]] = None

If F and G are both cats.Bitraverse then so is their composition F[G[_, _], G[_, _]]

The composition of two Bifunctors is itself a Bifunctor

apply a function to the "left" functor

Sequence the left side of the structure. For the right side, use the standard sequence from cats.Traverse.

Example:

scala> import cats.implicits._

scala> val optionalErrorRight: Either[Option[String], Int] = Either.right(123)
scala> optionalErrorRight.leftSequence
res1: Option[Either[String, Int]] = Some(Right(123))

scala> val optionalErrorLeftSome: Either[Option[String], Int] = Either.left(Some("something went wrong"))
scala> optionalErrorLeftSome.leftSequence
res2: Option[Either[String, Int]] = Some(Left(something went wrong))

scala> val optionalErrorLeftNone: Either[Option[String], Int] = Either.left(None)
scala> optionalErrorLeftNone.leftSequence
res3: Option[Either[String,Int]] = None

Traverse over the left side of the structure. For the right side, use the standard traverse from cats.Traverse.

Example:

scala> import cats.implicits._

scala> val intAndString: (Int, String) = (7, "test")

scala> Bitraverse[Tuple2].leftTraverse(intAndString)(i => Option(i).filter(_ > 5))
res1: Option[(Int, String)] = Some((7,test))

scala> Bitraverse[Tuple2].leftTraverse(intAndString)(i => Option(i).filter(_ < 5))
res2: Option[(Int, String)] = None

Widens A into a supertype AA. Example:

scala> import cats.implicits._
scala> sealed trait Foo
scala> case object Bar extends Foo
scala> val x1: Either[Bar.type, Int] = Either.left(Bar)
scala> val x2: Either[Foo, Int] = x1.leftWiden