Sum

Implements

Setoid, Semigroup, Monoid

Construction

Sum :: Number -> Sum Number

Sum provides addition on Numbers and needs to be constructed with a Number instance. Calling the constructor with a Number, results in a new Sum that wraps the provided Number.

Passing undefined, NaN or null to the constructor will result in an empty instance, or an instance containing a 0.

import Sum from 'crocks/Sum'

import equals from 'crocks/pointfree/equals'

Sum(41)
//=> Sum 41

Sum(Infinity)
//=> Sum Infinity

Sum(NaN)
//=> Sum 0

equals(Sum(undefined), Sum.empty())
//=> true

Constructor Methods

empty

Sum.empty :: () -> Sum

empty provides the identity for the Monoid in that when the value it provides is concated to any other value, it will return the other value. In the case of Sum the result of empty is 0. empty is available on both the Constructor and the Instance for convenience.

import Sum from 'crocks/Sum'

Sum.empty()
//=> Sum 0

Sum.empty()
  .concat(Sum.empty())
//=> Sum 0

Sum(4)
  .concat(Sum.empty())
//=> Sum 4

Sum.empty()
  .concat(Sum(4))
//=> Sum 4

Instance Methods

equals

Sum a ~> b -> Boolean

Used to compare the underlying values of (2) Sum instances for equality by value, equals takes any given argument and returns true if the passed argument is a Sum with an underlying value equal to the underlying value of the Sum the method is being called on. If the passed argument is not a Sum or the underlying values are not equal, equals will return false.

import Sum from 'crocks/Sum'

Sum(5)
  .equals(Sum(5))
//=> true

Sum(25)
  .equals(Sum(31))
//=> false

concat

Sum ~> Sum -> Sum

concat is used to combine (2) Semigroups of the same type under an operation specified by the Semigroup. In the case of Sum, it will add the (2) Numbers.

import Sum from 'crocks/Sum'

Sum(5)
  .concat(Sum(4))
//=> Sum 9

Sum(45)
  .concat(Sum(32))
//=> Sum 77

Sum(1000)
  .concat(Sum(Infinity))
//=> Sum Infinity

Sum(1)
  .concat(Sum(3))
//=> Sum 4

valueOf

Sum ~> () -> Number

valueOf is used on all crocks Monoids as a means of extraction. While the extraction is available, types that implement valueOf are not necessarily a Comonad. This function is used primarily for convenience for some of the helper functions that ship with crocks. Calling valueOf on a Sum instance will result in the underlying Number.

import Sum from 'crocks/Sum'

Sum(4)
  .valueOf()
//=> 4

Sum.empty()
  .valueOf()
//=> 0

Sum(34)
  .concat(Sum(21))
  .valueOf()
//=> 55