CommutativeArrow
Related Docs:
object CommutativeArrow
| package arrow
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)
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.
Contramap on the first type parameter and map on the second type parameter
Contramap on the first type parameter and map on the second type parameter
Example:
scala> import cats.implicits._ scala> import cats.arrow.Profunctor scala> val fab: Double => Double = x => x + 0.3 scala> val f: Int => Double = x => x.toDouble / 2 scala> val g: Double => Double = x => x * 3 scala> val h = Profunctor[Function1].dimap(fab)(f)(g) scala> h(3) res0: Double = 5.4
contramap on the first type parameter
contramap on the first type parameter
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.
map on the second type parameter
map on the second type parameter
Create a new F that takes two inputs, but only modifies the second input
Create a new F that takes two inputs, but only modifies the second input
Example:
scala> import cats.implicits._ scala> import cats.arrow.Strong scala> val f: Int => Int = _ * 2 scala> val fab = Strong[Function1].second[Int,Int,Int](f) scala> fab((2,3)) res0: (Int, Int) = (2,6)
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.
In a Commutative Arrow F[_, _], the split operation (or
***) is commutative, which means that there is non-interference between the effect of the paired arrows.Must obey the laws in CommutativeArrowLaws