RecyclerView plus Kotlin

AutoUpdatableAdapter.kt

interface AutoUpdatableAdapter {
    fun <T> RecyclerView.Adapter<*>.autoNotify(old: List<T>, new: List<T>, compare: (T, T) -> Boolean) {
        val diff = DiffUtil.calculateDiff(object : DiffUtil.Callback() {

            override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
                return compare(old[oldItemPosition], new[newItemPosition])
            }

            override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
                return old[oldItemPosition] == new[newItemPosition]
            }

            override fun getOldListSize() = old.size

            override fun getNewListSize() = new.size
        })
        diff.dispatchUpdatesTo(this)
    }
}

RecyclerEx.kt

fun RecyclerView.initRecycler(mAdapter: RecyclerView.Adapter<RecyclerView.ViewHolder>,
                              addDivider: Boolean = false,
                              spanCount: Int = 1,
                              @AnimRes animRes: Int = R.anim.layout_animation_fall_down,
                              spacing: Int = 32) =
        this.apply {
            layoutManager = if (spanCount == 1) LinearLayoutManager(context) else GridLayoutManager(context, spanCount)
            layoutAnimation = AnimationUtils.loadLayoutAnimation(context, animRes)
            if (spanCount == 1 && addDivider) addItemDecoration(DividerItemDecoration(context, DividerItemDecoration.VERTICAL))
            if (spacing != 0 && !addDivider) addItemDecoration(EqualSpacingItemDecoration(spacing))// 16px. In practice, you'll want to use getDimensionPixelSize
            adapter = mAdapter
        }