Question

I’m coding up my first Scala script to get a feel for the language, and I’m a bit stuck as to the best way to achieve something.

My situation is the following, I have a method which I need to call N times, this method returns an Int on each run (might be different, there’s a random component to the execution), and I want to keep the best run (the smallest value returned on these runs).

Now, coming from a Java/Python background, I would simply initialize the variable with null/None, and compare in the if, something like:

best = None
for...
    result = executionOfThings()
    if(best is None or result < best):
        best = result

And that’s that (pardon for the semi-python pseudo-code).

Now, on Scala, I’m struggling a bit. I’ve read about the usage of Option and pattern matching to achieve the same effect, and I guess I could code up something like (this was the best I could come up with):

best match {
    case None => best = Some(res)
    case Some(x) if x > res => best = Some(res)
    case _ =>
  }

I believe this works, but I’m not sure if it’s the most idiomatic way of writing it. It’s clear enough, but a bit verbose for such a simple “use-case”.

Anyone that could shine a functional light on me?

Thanks.

Answer 1

For this particular problem, not in general, I would suggest initializing with Int.MaxValue as long as you’re guaranteed that N >= 1. Then you just

if (result < best) best = result

You could also, with best as an option,

best = best.filter(_ >= result).orElse( Some(result) )

if the optionality is important (e.g. it is possible that N == 0, and you don’t take a distinct path through the code in that case). This is a more general way to deal with optional values that may get replaced: use filter to keep the non-replaced cases, and orElse to fill in the replacement if needed.