Assign - Crocks

Assign Object

Assign is a Monoid that will combine (2) objects under assignment using Object.assign on the (2) Objects.

import Assign from 'crocks/Assign'

const first = { name: 'Bob' }
const last = { lastName: 'Smith' }

Assign(first)
  .concat(Assign(last))
//=> Assign { name: 'Bob', lastName: 'Smith' }

Construction

Assign :: Object -> Assign Object

Assign is constructed by calling the constructor with an Object instance. This will return a new Assign instance, wrapping the reference to the provided Object.

import Assign from 'crocks/Assign'

Assign({ a: 123, b: false })
//=> Assign({ a: 123, b: false })

Constructor Methods

empty

Assign.empty :: () -> Assign

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

import Assign from 'crocks/Assign'

Assign.empty()
//=> Assign {}

Assign({})
  .concat(Assign.empty())
//=> Assign {}

Assign({ a: 1 })
  .concat(Assign.empty())
//=> Assign { a: 1 }

Instance Methods

equals

Assign a ~> b -> Boolean

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

import Assign from 'crocks/Assign'

Assign({ a: 5 })
  .equals(Assign({ a: 5 }))
//=> true

Assign({ a: 5 })
  .equals(Assign({ a: 15 }))
//=> false

concat

Assign ~> Assign -> Assign

concat is used to combine (2) Semigroups of the same type under an operation specified by the Semigroup. In the case of Assign, it will combine (2) objects, overwriting the first Object's previous values with the values of the second Object.

import Assign from 'crocks/Assign'

Assign({})
  .concat(Assign({}))
//=> Assign {}

Assign({ a: 1 })
  .concat(Assign({ b: 2 }))
//=> Assign { a: 1, b: 2 }

Assign({ a: 1, b: 2 })
  .concat(Assign({ a: 3, b: 4 }))
//=> Assign { a: 3, b: 4 }

Assign({ b: 4 })
  .concat(Assign({ a: 1 }))
//=> Assign { b: 4, a: 1 }

valueOf

Assign ~> () -> Object

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 an Assign instance will result in the underlying Object.

import Assign from 'crocks/Assign'

Assign({})
  .valueOf()
//=> {}

Assign({ a: 1 })
  .valueOf()
//=> { a: 1 }

Assign({ a: 1 })
  .concat({ b: 25 })
  .valueOf()
//=> { a: 1, b: 25 }