Problem Statement
Explain when and why you should use Sequences instead of regular collections for better performance.
Explanation
Use sequences when chaining multiple operations on large collections because sequences use lazy evaluation processing elements one at a time through the entire chain, avoiding intermediate collection creation. Collections eagerly create a new collection for each operation, which is wasteful for large datasets or when you don't need all results.
Sequences are beneficial when you have multiple transformations like filter then map then take, as each element flows through all operations before the next element starts, enabling short-circuiting operations to stop early. For small collections under 100 elements, the overhead of lazy evaluation makes sequences slower than eager collections.
Convert to sequence with asSequence, chain operations, and use terminal operations like toList, first, or count to trigger evaluation. Sequences can represent infinite streams processed on-demand, and they excel when dealing with IO operations or expensive computations where avoiding unnecessary work matters.
Avoid sequences for simple single operations or small data where collection overhead is negligible, and always benchmark performance-critical code since intuition about performance can be wrong.
Practice Sets
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