Function diff

packages/effect/src/internal/differ/contextPatch.ts:131–153

(
  oldValue: Context<Input>,
  newValue: Context<Output>
)

/** @internal */
export const diff = <Input, Output>(
  oldValue: Context<Input>,
  newValue: Context<Output>
): Differ.Context.Patch<Input, Output> => {
  const missingServices = new Map(oldValue.unsafeMap)
  let patch = empty<any, any>()
  for (const [tag, newService] of newValue.unsafeMap.entries()) {
    if (missingServices.has(tag)) {
      const old = missingServices.get(tag)!
      missingServices.delete(tag)
      if (!Equal.equals(old, newService)) {
        patch = combine(makeUpdateService(tag, () => newService))(patch)
      }
    } else {
      missingServices.delete(tag)
      patch = combine(makeAddService(tag, newService))(patch)
    }
  }
  for (const [tag] of missingServices.entries()) {
    patch = combine(makeRemoveService(tag))(patch)
  }
  return patch
}

/** @internal */
export const combine = Dual.dual<