this post was submitted on 05 Sep 2024
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Programming

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[–] [email protected] 5 points 3 months ago* (last edited 3 months ago) (1 children)

Honestly, it is much more code to use loop with non-local control like break, continue etc. (variable initialization, append, variable mutation in loops...) than just calling a collect function (which I assume just means to_list). In the above example, in most programming language I know, you don't even need to collect the result into a list.

Not to mention, large loops with non-local control is a breeding ground for spegatti code. Because you no longer have a consistent exit point to the loop, thus making the semantics hard o reason about.

In many languages, there are type class / trait / interfaces (whatever you want to call them) that allows lazy structures to share the same API as strict ones.

[–] [email protected] 3 points 3 months ago (1 children)

Yeah, in Java calling first() on a stream is the same as an early return in a for-loop, where for each element all of the previous stream operations are applied first.

So the stream operation

cars.stream()
    .filter(c -> c.year() < 1977)
    .first()

is equivalent to doing the following imperatively

for (var car : cars) {
    if (car.year() < 1977) return car;
}

Not to mention Kotlin actually supports non-local returns in lambdas under specific circumstances, which allows for even more circumstances to be expressed with functional chaining.

[–] nous 4 points 3 months ago (1 children)

These are not quite equivalent. In terms of short-circuiting yeah they both short-circuit when they get the value. But the latter is returning from the current function and the former is not. If you add a return to that first example then they are equivalent. But then cannot be used in line. Which is a nice advantage to the former - it can be used inline with less faff as you can just assign the return to a value. The latter needs you to declare a variable, assign it and break from the loop in the if.

Personally I quite like how the former requires less modification to work in different contexts and find it nicer to read. Though not all logic is easier to read with a stream, sometimes a good old for loop makes the code more readable. Use which ever helps you best at each point. Never blindly apply some pattern to every situation.

[–] [email protected] 4 points 3 months ago

Well yes, I was simplifying because I wanted to address the main (incorrect) criticism by @[email protected]. I agree with your comment