Must obey the laws defined in cats.laws.ArrowChoiceLaws.
- Companion:
- object
Value members
Abstract methods
ArrowChoice yields Arrows with choice, allowing distribution over coproducts.
ArrowChoice yields Arrows with choice, allowing distribution over coproducts.
Given two Fs (f and g), create a new F with
domain the coproduct of the domains of f and g,
and codomain the coproduct of the codomains of f and g.
This is the sum notion to split's product.
Example:
scala> import cats.implicits._
scala> val toLong: Int => Long = _.toLong
scala> val toDouble: Float => Double = _.toDouble
scala> val f: Either[Int, Float] => Either[Long, Double] = toLong +++ toDouble
scala> f(Left(3))
res0: Either[Long,Double] = Left(3)
scala> f(Right(3))
res1: Either[Long,Double] = Right(3.0)
Concrete methods
Inherited methods
An F that, given a source A on either the right or left side, will
return that same A object.
An F that, given a source A on either the right or left side, will
return that same A object.
Example:
scala> import cats.implicits._
scala> val f: (Either[Int, Int]) => Int = Choice[Function1].codiagonal[Int]
scala> f(Right(3))
res0: Int = 3
scala> f(Left(3))
res1: Int = 3
- Inherited from:
- Choice
Create a new F that takes two inputs, but only modifies the first input
Create a new F that takes two inputs, but only modifies the first input
Example:
scala> import cats.implicits._
scala> import cats.arrow.Strong
scala> val f: Int => Int = _ * 2
scala> val fab = Strong[Function1].first[Int,Int,Int](f)
scala> fab((2,3))
res0: (Int, Int) = (4,3)
- Inherited from:
- Strong
Narrows A into a subtype AA. Example:
Narrows A into a subtype AA. Example:
scala> import cats.syntax.profunctor._
scala> import cats.instances.function._
scala>
scala> sealed trait Foo
scala> case object Bar extends Foo
scala> val x1: Foo => Int = _ => 1
scala> val x2: Bar.type => Int = x1.leftNarrow
- Inherited from:
- Profunctor
Lift a function into the context of an Arrow.
Lift a function into the context of an Arrow.
In the reference articles "Arrows are Promiscuous...", and in the corresponding Haskell
library Control.Arrow, this function is called arr.
- Inherited from:
- Arrow
contramap on the first type parameter
contramap on the first type parameter
- Inherited from:
- Profunctor
Create a new computation F that merge outputs of f and g both having the same input
Create a new computation F that merge outputs of f and g both having the same input
Example:
scala> import cats.implicits._
scala> val addEmpty: Int => Int = _ + 0
scala> val multiplyEmpty: Int => Double= _ * 1d
scala> val f: Int => (Int, Double) = addEmpty &&& multiplyEmpty
scala> f(1)
res0: (Int, Double) = (1,1.0)
Note that the arrow laws do not guarantee the non-interference between the effects of
f and g in the context of F. This means that f &&& g may not be equivalent to g &&& f.
- Inherited from:
- Arrow
Widens B into a supertype BB. Example:
Widens B into a supertype BB. Example:
scala> import cats.syntax.profunctor._
scala> import cats.instances.function._
scala>
scala> sealed trait Foo
scala> case object Bar extends Foo
scala> val x1: Int => Bar.type = _ => Bar
scala> val x2: Int => Foo = x1.rightWiden
- Inherited from:
- Profunctor
Create a new computation F that splits its input between f and g
and combines the output of each.
Create a new computation F that splits its input between f and g
and combines the output of each.
Example:
scala> import cats.implicits._
scala> import cats.arrow.Arrow
scala> val toLong: Int => Long = _.toLong
scala> val toDouble: Float => Double = _.toDouble
scala> val f: ((Int, Float)) => (Long, Double) = Arrow[Function1].split(toLong, toDouble)
scala> f((3, 4.0f))
res0: (Long, Double) = (3,4.0)
Note that the arrow laws do not guarantee the non-interference between the effects of
f and g in the context of F. This means that f *** g may not be equivalent to g *** f.
- Inherited from:
- Arrow