given_CommutativeApply_ZipTree
Value members
Concrete methods
Inherited methods
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
ap2 is a binary version of ap, defined in terms of ap.
ap2 is a binary version of ap, defined in terms of ap.
- Inherited from
- Apply
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
Replaces the A
value in F[A]
with the supplied value.
Replaces the A
value in F[A]
with the supplied value.
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForList
scala> Functor[List].as(List(1,2,3), "hello")
res0: List[String] = List(hello, hello, hello)
- Inherited from
- Functor
Compose an Apply[F]
and an Apply[G]
into an Apply[λ[α => F[G[α]]]]
.
Compose an Apply[F]
and an Apply[G]
into an Apply[λ[α => F[G[α]]]]
.
Example:
scala> import cats.implicits._
scala> val alo = Apply[List].compose[Option]
scala> alo.product(List(None, Some(true), Some(false)), List(Some(2), None))
res1: List[Option[(Boolean, Int)]] = List(None, None, Some((true,2)), None, Some((false,2)), None)
- Inherited from
- Apply
Compose Invariant F[_]
and G[_]
then produce Invariant[F[G[_]]]
using their imap
.
Compose Invariant F[_]
and G[_]
then produce Invariant[F[G[_]]]
using their imap
.
Example:
scala> import cats.implicits._
scala> import scala.concurrent.duration._
scala> val durSemigroupList: Semigroup[List[FiniteDuration]] =
| Invariant[Semigroup].compose[List].imap(Semigroup[List[Long]])(Duration.fromNanos)(_.toNanos)
scala> durSemigroupList.combine(List(2.seconds, 3.seconds), List(4.seconds))
res1: List[FiniteDuration] = List(2 seconds, 3 seconds, 4 seconds)
- Inherited from
- Invariant
Compose Invariant F[_]
and Functor G[_]
then produce Invariant[F[G[_]]]
using F's imap
and G's map
.
Compose Invariant F[_]
and Functor G[_]
then produce Invariant[F[G[_]]]
using F's imap
and G's map
.
Example:
scala> import cats.implicits._
scala> import scala.concurrent.duration._
scala> val durSemigroupList: Semigroup[List[FiniteDuration]] =
| Invariant[Semigroup]
| .composeFunctor[List]
| .imap(Semigroup[List[Long]])(Duration.fromNanos)(_.toNanos)
scala> durSemigroupList.combine(List(2.seconds, 3.seconds), List(4.seconds))
res1: List[FiniteDuration] = List(2 seconds, 3 seconds, 4 seconds)
- Inherited from
- Invariant
Alias for map, since map can't be injected as syntax if
the implementing type already had a built-in .map
method.
Alias for map, since map can't be injected as syntax if
the implementing type already had a built-in .map
method.
Example:
scala> import cats.implicits._
scala> val m: Map[Int, String] = Map(1 -> "hi", 2 -> "there", 3 -> "you")
scala> m.fmap(_ ++ "!")
res0: Map[Int,String] = Map(1 -> hi!, 2 -> there!, 3 -> you!)
- Inherited from
- Functor
Tuple the values in fa with the result of applying a function with the value
Tuple the values in fa with the result of applying a function with the value
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForOption
scala> Functor[Option].fproduct(Option(42))(_.toString)
res0: Option[(Int, String)] = Some((42,42))
- Inherited from
- Functor
Pair the result of function application with A
.
Pair the result of function application with A
.
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForOption
scala> Functor[Option].fproductLeft(Option(42))(_.toString)
res0: Option[(String, Int)] = Some((42,42))
- Inherited from
- Functor
An if-then-else
lifted into the F
context.
This function combines the effects of the fcond
condition and of the two branches,
in the order in which they are given.
An if-then-else
lifted into the F
context.
This function combines the effects of the fcond
condition and of the two branches,
in the order in which they are given.
The value of the result is, depending on the value of the condition, the value of the first argument, or the value of the second argument.
Example:
scala> import cats.implicits._
scala> val b1: Option[Boolean] = Some(true)
scala> val asInt1: Option[Int] = Apply[Option].ifA(b1)(Some(1), Some(0))
scala> asInt1.get
res0: Int = 1
scala> val b2: Option[Boolean] = Some(false)
scala> val asInt2: Option[Int] = Apply[Option].ifA(b2)(Some(1), Some(0))
scala> asInt2.get
res1: Int = 0
scala> val b3: Option[Boolean] = Some(true)
scala> val asInt3: Option[Int] = Apply[Option].ifA(b3)(Some(1), None)
asInt2: Option[Int] = None
- Inherited from
- Apply
Lifts if
to Functor
Lifts if
to Functor
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForList
scala> Functor[List].ifF(List(true, false, false))(1, 0)
res0: List[Int] = List(1, 0, 0)
- Inherited from
- Functor
Lift a function f to operate on Functors
Lift a function f to operate on Functors
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForOption
scala> val o = Option(42)
scala> Functor[Option].lift((x: Int) => x + 10)(o)
res0: Option[Int] = Some(52)
- Inherited from
- Functor
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
Applies the pure (binary) function f to the effectful values fa and fb.
Applies the pure (binary) function f to the effectful values fa and fb.
map2 can be seen as a binary version of cats.Functor#map.
Example:
scala> import cats.implicits._
scala> val someInt: Option[Int] = Some(3)
scala> val noneInt: Option[Int] = None
scala> val someLong: Option[Long] = Some(4L)
scala> val noneLong: Option[Long] = None
scala> Apply[Option].map2(someInt, someLong)((i, l) => i.toString + l.toString)
res0: Option[String] = Some(34)
scala> Apply[Option].map2(someInt, noneLong)((i, l) => i.toString + l.toString)
res0: Option[String] = None
scala> Apply[Option].map2(noneInt, noneLong)((i, l) => i.toString + l.toString)
res0: Option[String] = None
scala> Apply[Option].map2(noneInt, someLong)((i, l) => i.toString + l.toString)
res0: Option[String] = None
- Inherited from
- Apply
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
Similar to map2 but uses Eval to allow for laziness in the F[B]
argument. This can allow for "short-circuiting" of computations.
Similar to map2 but uses Eval to allow for laziness in the F[B]
argument. This can allow for "short-circuiting" of computations.
NOTE: the default implementation of map2Eval
does not short-circuit
computations. For data structures that can benefit from laziness, Apply
instances should override this method.
In the following example, x.map2(bomb)(_ + _)
would result in an error,
but map2Eval
"short-circuits" the computation. x
is None
and thus the
result of bomb
doesn't even need to be evaluated in order to determine
that the result of map2Eval
should be None
.
scala> import cats.{Eval, Later}
scala> import cats.implicits._
scala> val bomb: Eval[Option[Int]] = Later(sys.error("boom"))
scala> val x: Option[Int] = None
scala> x.map2Eval(bomb)(_ + _).value
res0: Option[Int] = None
- Inherited from
- Apply
Compose two actions, discarding any value produced by the second.
Compose two actions, discarding any value produced by the second.
- See also
productR to discard the value of the first instead. Example:
scala> import cats.implicits._ scala> import cats.data.Validated scala> import Validated.{Valid, Invalid} scala> type ErrOr[A] = Validated[String, A] scala> val validInt: ErrOr[Int] = Valid(3) scala> val validBool: ErrOr[Boolean] = Valid(true) scala> val invalidInt: ErrOr[Int] = Invalid("Invalid int.") scala> val invalidBool: ErrOr[Boolean] = Invalid("Invalid boolean.") scala> Apply[ErrOr].productL(validInt)(validBool) res0: ErrOr[Int] = Valid(3) scala> Apply[ErrOr].productL(invalidInt)(validBool) res1: ErrOr[Int] = Invalid(Invalid int.) scala> Apply[ErrOr].productL(validInt)(invalidBool) res2: ErrOr[Int] = Invalid(Invalid boolean.) scala> Apply[ErrOr].productL(invalidInt)(invalidBool) res3: ErrOr[Int] = Invalid(Invalid int.Invalid boolean.)
- Inherited from
- Apply
Compose two actions, discarding any value produced by the first.
Compose two actions, discarding any value produced by the first.
- See also
productL to discard the value of the second instead. Example:
scala> import cats.implicits._ scala> import cats.data.Validated scala> import Validated.{Valid, Invalid} scala> type ErrOr[A] = Validated[String, A] scala> val validInt: ErrOr[Int] = Valid(3) scala> val validBool: ErrOr[Boolean] = Valid(true) scala> val invalidInt: ErrOr[Int] = Invalid("Invalid int.") scala> val invalidBool: ErrOr[Boolean] = Invalid("Invalid boolean.") scala> Apply[ErrOr].productR(validInt)(validBool) res0: ErrOr[Boolean] = Valid(true) scala> Apply[ErrOr].productR(invalidInt)(validBool) res1: ErrOr[Boolean] = Invalid(Invalid int.) scala> Apply[ErrOr].productR(validInt)(invalidBool) res2: ErrOr[Boolean] = Invalid(Invalid boolean.) scala> Apply[ErrOr].productR(invalidInt)(invalidBool) res3: ErrOr[Boolean] = Invalid(Invalid int.Invalid boolean.)
- Inherited from
- Apply
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
- Inherited from
- ApplyArityFunctions
Tuples the A
value in F[A]
with the supplied B
value, with the B
value on the left.
Tuples the A
value in F[A]
with the supplied B
value, with the B
value on the left.
Example:
scala> import scala.collection.immutable.Queue
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForQueue
scala> Functor[Queue].tupleLeft(Queue("hello", "world"), 42)
res0: scala.collection.immutable.Queue[(Int, String)] = Queue((42,hello), (42,world))
- Inherited from
- Functor
Tuples the A
value in F[A]
with the supplied B
value, with the B
value on the right.
Tuples the A
value in F[A]
with the supplied B
value, with the B
value on the right.
Example:
scala> import scala.collection.immutable.Queue
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForQueue
scala> Functor[Queue].tupleRight(Queue("hello", "world"), 42)
res0: scala.collection.immutable.Queue[(String, Int)] = Queue((hello,42), (world,42))
- Inherited from
- Functor
Un-zips an F[(A, B)]
consisting of element pairs or Tuple2 into two separate F's tupled.
Un-zips an F[(A, B)]
consisting of element pairs or Tuple2 into two separate F's tupled.
NOTE: Check for effect duplication, possibly memoize before
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForList
scala> Functor[List].unzip(List((1,2), (3, 4)))
res0: (List[Int], List[Int]) = (List(1, 3),List(2, 4))
- Inherited from
- Functor
Empty the fa of the values, preserving the structure
Empty the fa of the values, preserving the structure
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForList
scala> Functor[List].void(List(1,2,3))
res0: List[Unit] = List((), (), ())
- Inherited from
- Functor
Lifts natural subtyping covariance of covariant Functors.
Lifts natural subtyping covariance of covariant Functors.
NOTE: In certain (perhaps contrived) situations that rely on universal
equality this can result in a ClassCastException
, because it is
implemented as a type cast. It could be implemented as map(identity)
, but
according to the functor laws, that should be equal to fa
, and a type
cast is often much more performant.
See this example
of widen
creating a ClassCastException
.
Example:
scala> import cats.Functor
scala> import cats.implicits.catsStdInstancesForOption
scala> val s = Some(42)
scala> Functor[Option].widen(s)
res0: Option[Int] = Some(42)
- Inherited from
- Functor