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Discrete.scala
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Discrete.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.collections
/**
* Represent discrete operations that can be performed on A
*/
trait Discrete[@specialized(Specializable.Integral) A] extends Serializable {
/**
* Return the successor of x.
*/
def succ(x: A): A
/**
* Returns the predecessor of x.
*/
def pred(x: A): A
/**
* Returns true if x and y are consecutive.
*/
def adj(x: A, y: A): Boolean = succ(x) == y
/**
* Returns the inverse of this discrete (succ and pred are flipped).
*/
def inverse: Discrete[A] =
Discrete.inverse(this)
}
object Discrete {
/**
* Summons an implicit instance of Discrete[A] from the implicit scope.
*/
@inline final def apply[A](implicit instance: Discrete[A]): Discrete[A] =
instance
/**
* Returns the inverse of the provided discrete (succ and pred are flipped).
*/
final def inverse[A](discrete: Discrete[A]): Discrete[A] =
new Discrete[A] {
override def succ(x: A): A = discrete.pred(x)
override def pred(x: A): A = discrete.succ(x)
}
implicit def integralDiscrete[@specialized(Specializable.Integral) I](implicit I: Integral[I]): Discrete[I] =
new Discrete[I] {
import Integral.Implicits._
override def succ(x: I): I = x + I.one
override def pred(x: I): I = x - I.one
}
}