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InvariantMonoidal.scala
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InvariantMonoidal.scala
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/*
* Copyright (c) 2015 Typelevel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package cats
/**
* Invariant version of a Monoidal.
*
* Must obey the laws defined in cats.laws.InvariantMonoidalLaws.
*/
trait InvariantMonoidal[F[_]] extends InvariantSemigroupal[F] {
/**
* `point` lifts any value into a Monoidal Functor.
*
* Example:
* {{{
* scala> import cats.syntax.all._
*
* scala> InvariantMonoidal[Option].point(10)
* res0: Option[Int] = Some(10)
* }}}
*/
def point[A](a: A): F[A] = imap(unit)(_ => a)(_ => ())
def unit: F[Unit]
}
object InvariantMonoidal {
/**
* Gives a `Monoid` instance if A itself has a `Monoid` instance.
*/
def monoid[F[_], A](implicit F: InvariantMonoidal[F], A: Monoid[A]): Monoid[F[A]] =
new InvariantMonoidalMonoid[F, A](F, A)
/**
* Summon an instance of [[InvariantMonoidal]] for `F`.
*/
@inline def apply[F[_]](implicit instance: InvariantMonoidal[F]): InvariantMonoidal[F] = instance
@deprecated("Use cats.syntax object imports", "2.2.0")
object ops {
implicit def toAllInvariantMonoidalOps[F[_], A](target: F[A])(implicit tc: InvariantMonoidal[F]): AllOps[F, A] {
type TypeClassType = InvariantMonoidal[F]
} =
new AllOps[F, A] {
type TypeClassType = InvariantMonoidal[F]
val self: F[A] = target
val typeClassInstance: TypeClassType = tc
}
}
trait Ops[F[_], A] extends Serializable {
type TypeClassType <: InvariantMonoidal[F]
def self: F[A]
val typeClassInstance: TypeClassType
}
trait AllOps[F[_], A] extends Ops[F, A] with InvariantSemigroupal.AllOps[F, A] {
type TypeClassType <: InvariantMonoidal[F]
}
trait ToInvariantMonoidalOps extends Serializable {
implicit def toInvariantMonoidalOps[F[_], A](target: F[A])(implicit tc: InvariantMonoidal[F]): Ops[F, A] {
type TypeClassType = InvariantMonoidal[F]
} =
new Ops[F, A] {
type TypeClassType = InvariantMonoidal[F]
val self: F[A] = target
val typeClassInstance: TypeClassType = tc
}
}
@deprecated("Use cats.syntax object imports", "2.2.0")
object nonInheritedOps extends ToInvariantMonoidalOps
}
private[cats] class InvariantMonoidalMonoid[F[_], A](f: InvariantMonoidal[F], monoid: Monoid[A])
extends InvariantSemigroupalSemigroup(f, monoid)
with Monoid[F[A]] {
def empty: F[A] = f.point(monoid.empty)
}