In Immutable.js, we use sequences to chain together transformation method calls. Using sequences this way, we're doing something called lazy evaluation; that is, we only process data from collections that actually need to be processed. Without lazy evaluation, we would have to process entire collections or come up with some other means to avoid processing work.
Why lazy evaluation?
Large collections are expensive
A large collection is a collection that contains enough values that the cost of processing it becomes a cause for concern. Depending on the application—where it runs, who uses it, and how the collections are processed—a large collection could be anywhere from 500 to 10,000+ values.
Generally speaking...
