Pattern Matching Tricks in Scala | Rock the JVM

This video is for the Scala programmer who's only been using pattern matching in its basic form: either as a switch-on-steroids, or to deconstruct case classes. I will show you 8 tricks to use PM to its full power, so that you write clean code, test exactly what you want, and save others from the pain of reading duplicates.

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[artyom.shootov]

Another trick is pattern matching against an interpolated string:
def greet(str: String) = str match {
case s"Hello, ${name}" => println(s"$name has joined")
case _ => println("Someone has joined")
}

[katabd]

Wow.. love the video. Been using Scala for a while at work and learning while I go but haven't seen these types of pattern matching tricks. Learnt a lot of value from this. thanks.

[simonfarre]

This is why I *love* rust. A low level systems language with pattern matching. Pattern. matching. is. incredibly. ergonomic.

[jeremygiaco]

Thanks for the tricks. I haven't used scala for a few years and am diving back into it. Pretty helpful!

[rheafernandeshallu]

Thank you so much for your tips and tricks. I love scala, but I find very little quality content related to it.

[Peter-xnbk]

I have learned two course of you at Udemy, nice guide. Thankyou

[davidsljukic]

Awesome tutorial series. Really enjoying working out the examples alongside the video \m\

[theanigos]

Very useful in data engineering space as well for routing different data flow with some complex conditions. Liked it!

[alanlewis]

Hi Daniel, another very good video, as usual. Albeit, with a tiny error, in the numbers list, appending the "st", "nd", ... would not work with 11 or 12... Please keep up the great work with the Rock the JVM content. Thanks

[hinrikmarhreinsson]

Would you use pattern matching when parsing stream of data from Kafka or other databases? Do you know of a good flink + Scala tutorial?

[mikepictor]

I am wondering in your alternative patterns example, could you end in "case n" instead of "case _" ... to keep the processing more visually consistent to the examples above it.

[vitorfilho]

Great video, but i had a question, assuming I have several objects and these objects have a main function, which receive parameters something like this:
object a {def main {p1, p2} in my another object i want to pass for this object using a match case paramater match {case paramater => a{p1, p2}. Is there any way for me to parameterize this object call too, because in this case I will have several objects that depend on this parameter match case?

[bitcoindaddy]

Video is great, the blog page in the description does not work btw.

[Tangxx]

The video is superb! Thank you so much as I'm struggling to find quality content like this. Also, it would be more favourable if you could provide the source code as well! Thank you so much!

[drishtinishchhalsahu]

Hi, I get the same error in trick 2 process method.
My Code -
def process(aList: List[Int]) = aList match
{
case Nil => "list is empty"
case head :: tail => s"list starts with $head, tail is $tail"
}



Error - process: (aList: List[Int])String

[shumymikaball]

Can I use this with type literals to build a parser, instead of using antlr?

[gijduvon]

Daniel,
do you planning to make videos about cats?

[drishtinishchhalsahu]

Hi Thanks for the amazing videos, i am beginner in scala. I have tried trick#2 example from above, but i am getting below error. I am practising above example in scala worksheet.


My Code -
val numberList = List(1, 2, 3, 4)


val startWithOne = numberList match {
case 1 :: tail => s"list start with one, tail is $tail"
}


Error Message -
numberList: List[Int] = List(1, 2, 3, 4)


^
warning: match may not be exhaustive.
It would fail on the following inputs: List((x: Int forSome x not in 1)), Nil
startWithOne: String = list start with one, tail is List(2, 3, 4)

[fakirrabih]

Thank you for the videos, very concise and helpful, I have a situation where my stream generated column “value” has a composite number something like: 0112547.21 the first 4 digits are the ID (0112) the rest is the value 547.21 what is best to decompose the column tried to use the regex but without success and here is what I tried to do as the first item to be extracted:
Item12: Regex = "((?s)(?<=^(01)12)\\w+)".r,

Appreciate Any help and support
Thanks again

[kailar]

what is the purpose of your main method without showing results how a beginner will learn.
Good Material with poor presentation for beginners. Your intension is people should not learn