//arrow-core/arrow.typeclasses/Semiring

Semiring

common interface Semiring<A>

The Semiring type class for a given type A combines both a commutative additive Monoid and a multiplicative Monoid. It requires the multiplicative Monoid to distribute over the additive one. The operations of the multiplicative Monoid have been renamed to one and combineMultiplicate for easier use.

(a.combineMultiplicate(b)).combineMultiplicate(c) == a.combineMultiplicate(b.combineMultiplicate(c))

The one function serves exactly like the empty function for an additive Monoid, just adapted for the multiplicative version. This forms the following law:

a.combineMultiplicate(one()) == one().combineMultiplicate(a) == a

Please note that the empty function has been renamed to zero to get a consistent naming style inside the semiring.

Currently, Semiring instances are defined for all available number types.

Examples

Here a some examples:

import arrow.typeclasses.Semiring

fun main(args: Array<String>) {
  val result =
  //sampleStart
  Semiring.int().run { 1.combine(2) }
  //sampleEnd
  println(result)
}

import arrow.typeclasses.Semiring

fun main(args: Array) { val result = //sampleStart Semiring.int().run { 2.combineMultiplicate(3) } //sampleEnd println(result) }


The type class `Semiring` also has support for the `+``*` syntax:

{: data-executable='true'}

```kotlin
import arrow.typeclasses.Semiring

fun main(args: Array<String>) {
  val result =
  //sampleStart
  Semiring.int().run {
     1 + 2
  }
  //sampleEnd
  println(result)
}

import arrow.typeclasses.Semiring

fun main(args: Array) { val result = //sampleStart Semiring.int().run { 2 * 3 } //sampleEnd println(result) } ```

Types

Name Summary
Companion common object Companion

Functions

Name Summary
combine common abstract fun A.combine(b: A): A
combineMultiplicate common abstract fun A.combineMultiplicate(b: A): A
Multiplicatively combine two A values.
maybeCombineAddition common open fun A?.maybeCombineAddition(b: A?): A
Maybe additively combine two A values.
maybeCombineMultiplicate common open fun A?.maybeCombineMultiplicate(b: A?): A
Maybe multiplicatively combine two A values.
one common abstract fun one(): A
A one value for this A
plus common open operator fun A.plus(b: A): A
times common open operator fun A.times(b: A): A
zero common abstract fun zero(): A
A zero value for this A

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