Hi all, is this the best approach of finding a specific item in a list based on a certain predicate ...

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[svenjacobs]

Hi all, is this the best approach of finding a specific item in a list based on a certain predicate and returning the item's index and value at once?

list.asSequence().withIndex().find { some predicate }

[streetsofboston]

Not sure if asSequence() is necessary...

[svenjacobs]

I think asSequence() makes sense because then the values are computed lazily. So if the predicate matches the second item of the list out of 500, then only two IndexedValue needed to be created and 498 IndexedValue where never created 🙂

[marstran]

withIndex on a list actually returns a lazy iterable: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/with-index.html

[svenjacobs]

@marstran No 😉 Sequence has it's own implementation of withIndex.

[marstran]

Sure, but read the doc. It says "Returns a lazy Iterable that wraps each element ...".

[svenjacobs]

Regarding an Iterable you're correct, but that's the reason why I convert the list to a Sequence first

[marstran]

But you don't need to, because the iterable returned by list.withIndex() is just as lazy as the sequence.

[marstran]

It doesn't create the other 498 indexed values.

[svenjacobs]

Ah, now I get what you mean 👍🏼