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kotlinlang

Hi, Is there any guidelines when to use sequences vs normal collection operations with some dataset?  Is there overhead if sequence is used with small dataset?

in general, the main difference is this: in regular collection ops, each operation is run on every element. in sequence/stream operations, all the operations are concatenated into a "pipeline" of sorts, which is then run on every element **lazily** when a terminal operation is invoked

for example, the `anyMatch((T)-&gt;Boolean)` sequence/stream terminal op will run the whole pipeline for every element until a matching element is found; no processing will be done on the rest of the stream.
a similar collection op, on the other hand, will run each stage in the pipeline on the whole collection, and then look for something that matches the predicate.

basically: if you have a long series of ops, use sequence/stream and you'll see more significant benefits the larger the dataset. for short series of ops, especially with small datasets, I don't think it really matters.

<https://medium.com/@ajalt/benchmarking-kotlin-sequences-e06d8bb4011c|https://medium.com/@ajalt/benchmarking-kotlin-sequences-e06d8bb4011c>

is a bit too simplistic, but the conclusion is reasonable

I wonder how the same benchmark would be now, given that stuff (I hope) has improved since Kotlin 1.2.70.
Also, I think it depends a lot on what type of operation we're talking about.

<https://typealias.com/guides/when-to-use-sequences/>