/**
 * `Equivalence<A>` provides evidence that two values of type `A` can be
 * compared for equality.
 *
 * @tsplus type Equivalence
 */
export interface Equivalence<A> {
  readonly Law: {
    readonly Equivalence: "Equivalence"
  }
  /**
   * Returns whether two values of type `A` are equal.
   */
  readonly equals: (x: A, y: A) => boolean
}

/**
 * @tsplus type Equivalence/Ops
 */
export interface EquivalenceOps {
  /**
   * Constructs an `Equal<A>` from a function. The instance will be optimized
   * to first compare the values for reference equality and then compare the
   * values for value equality.
   */
  <A>(equals: (x: A, y: A) => boolean): Equivalence<A>
  readonly $: EquivalenceAspects
}
export const Equivalence: EquivalenceOps = Object.assign(
  <A>(equals: (x: A, y: A) => boolean): Equivalence<A> => HKT.instance({ equals }),
  { $: {} }
)

/**
 * @tsplus type Equivalence/Aspects
 */
export interface EquivalenceAspects {}