Последние новости
Transforms don't execute until the consumer pulls. There's no eager evaluation, no hidden buffering. Data flows on-demand from source, through transforms, to the consumer. If you stop iterating, processing stops.
，这一点在旺商聊官方下载中也有详细论述
Step 3: Refine with Detailed Shortcuts (Applying Secret Sauce #2):
On the fourth loop iteration, the backing store of size 4 has only 3