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How to chain operations in idiomatic scala


How to chain operations in idiomatic scala

By : Vladimir Makarevich
Date : November 21 2020, 11:01 PM
this will help I want to apply a list of regex to a string. My current approach is not very functional , I think this does what you're looking for.
code :
def CanonicalName(name: String): String = {
  val stopWords = List("the", "restaurant", "bar", "[^a-zA-Z -]")
  stopWords.foldLeft(name)(_.replaceAll(_, "")).replaceAll(" +"," ").trim
}


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Scala data structures: chain of operations (such as mapValues, filter ...) and intermediate results

Scala data structures: chain of operations (such as mapValues, filter ...) and intermediate results


By : FilipposA
Date : March 29 2020, 07:55 AM
I wish this helpful for you Consider the following: , This seems to do the trick:
code :
object  ChainOpsRS
{
  val stuff = Map[String, Int]("apple" -> 5, "orange" -> 1, "banana" -> 3, "kiwi" -> 2)

  val used = 1

  val rest =
    stuff.collect {
      case (fruit, quantity) if quantity > used => (fruit, quantity - used)
    }

  def main(args: Array[String]) {
    printf("stuff=%s%n", stuff.mkString("{", ", ", "}"))
    printf(" rest=%s%n", rest.mkString("{", ", ", "}"))
  }
}
stuff={apple -> 5, orange -> 1, banana -> 3, kiwi -> 2}
 rest={apple -> 4, banana -> 2, kiwi -> 1}
Idiomatic way in scala to emulate/replace unary addition for repeated operations

Idiomatic way in scala to emulate/replace unary addition for repeated operations


By : Neil Thomson
Date : March 29 2020, 07:55 AM
To fix this issue You're approaching the problem imperatively. Idiomatic Scala is more about functional programming. You have to get used to treating functions as values and exploit that power.
Your problem can be solved functionally like this:
code :
toks
  // Get a lazy wrapper around `toks`, so that all the subsequent
  // operations will be done in just a single traversal:
  .view 
  // Pair each item of `toks` up with an according operation:
  .zip(List(someOperation(_), nextOperation(_), subsequentOperation(_)))
  // Traverse thru those pairs, applying the operations:
  .foreach{ case (t, f) => f(t) }
Idiomatic Scala for Options in place of if/else/else chain

Idiomatic Scala for Options in place of if/else/else chain


By : user3538078
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further I know I am way late to the party, but feel that the orElse solution here is a bit clumsy. For me, the general functional idiom (not just scalaic) would be sth. along these lines (forgive me, I am not scala proficient):
code :
def f1 = () => { println("f1 here"); null }
def f2 = () => { println("f2 here"); null }
def f3 = () => { println("f3 here"); 2 }
def f4 = () => { println("f4 here"); 3 }
def f5 = () => { println("f5 here"); 43 }

Stream(f1, f2, f3, f4, f5)
  .map(f => f())
  .dropWhile(_ == null)
  .head
Idiomatic Scala for applying functions in a chain if Option(s) are defined

Idiomatic Scala for applying functions in a chain if Option(s) are defined


By : Marco Angaroni
Date : March 29 2020, 07:55 AM
it helps some times Scala has a way to do this with for comprehensions (The syntax is similar to haskell's do notation if you are familiar with it):
How to write idiomatic Scala wrapper classes to represent non idiomatic JSON

How to write idiomatic Scala wrapper classes to represent non idiomatic JSON


By : EmK4
Date : March 29 2020, 07:55 AM
Any of those help Your post mentioned you'd thought about building a Reads based on mapping order of arguments; that'd certainly be cumbersome. Did you look into creating a custom Read using the JSON Combinators that were introduced in Play! 2.1? The burden is a bit lower there; it's order insensitive
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