learning scala for comprehensions

code:

package com.aura.scala.day01

object forComprehensions {
  def main(args: Array[String]): Unit = {
    val userBase = List(User("pan1", 29), User("pan2", 30), User("pan3", 23), User("pan5", 32))
    val twentySomethins = for (userYonger <- userBase if userYonger.age > 20 && userYonger.age < 30)
      yield userYonger.name
    twentySomethins.foreach(name => println(name))

    def foo(n: Int, v: Int) =
      for (i <- 0 until n; j <- i until n if i + j == v)
        yield (i, j)

    foo(10,10).foreach {
      case(i,j ) => println(s"($i,$j)")
    }
  }
}

case class User(name: String, age: Int)

result:

"D:Program FilesJavajdk1.8.0_201injava.exe" "-javaagent:D:Program FilesJetBrainsIntelliJ IDEA 2019.1.3libidea_rt.jar=10892:D:Program FilesJetBrainsIntelliJ IDEA 2019.1.3in" -Dfile.encoding=UTF-8 -classpath "D:Program FilesJavajdk1.8.0_201jrelibcharsets.jar;D:Program FilesJavajdk1.8.0_201jrelibdeploy.jar;D:Program FilesJavajdk1.8.0_201jrelibextaccess-bridge-64.jar;D:Program FilesJavajdk1.8.0_201jrelibextcldrdata.jar;D:Program FilesJavajdk1.8.0_201jrelibextdnsns.jar;D:Program FilesJavajdk1.8.0_201jrelibextjaccess.jar;D:Program FilesJavajdk1.8.0_201jrelibextjfxrt.jar;D:Program FilesJavajdk1.8.0_201jrelibextlocaledata.jar;D:Program FilesJavajdk1.8.0_201jrelibext
ashorn.jar;D:Program FilesJavajdk1.8.0_201jrelibextsunec.jar;D:Program FilesJavajdk1.8.0_201jrelibextsunjce_provider.jar;D:Program FilesJavajdk1.8.0_201jrelibextsunmscapi.jar;D:Program FilesJavajdk1.8.0_201jrelibextsunpkcs11.jar;D:Program FilesJavajdk1.8.0_201jrelibextzipfs.jar;D:Program FilesJavajdk1.8.0_201jrelibjavaws.jar;D:Program FilesJavajdk1.8.0_201jrelibjce.jar;D:Program FilesJavajdk1.8.0_201jrelibjfr.jar;D:Program FilesJavajdk1.8.0_201jrelibjfxswt.jar;D:Program FilesJavajdk1.8.0_201jrelibjsse.jar;D:Program FilesJavajdk1.8.0_201jrelibmanagement-agent.jar;D:Program FilesJavajdk1.8.0_201jrelibplugin.jar;D:Program FilesJavajdk1.8.0_201jrelib
esources.jar;D:Program FilesJavajdk1.8.0_201jrelib
t.jar;C:UsersadminIdeaProjectsScalaDayoutproductionScalaDay;C:Program Files (x86)scalalibscala-actors-2.11.0.jar;C:Program Files (x86)scalalibscala-actors-migration_2.11-1.1.0.jar;C:Program Files (x86)scalalibscala-library.jar;C:Program Files (x86)scalalibscala-parser-combinators_2.11-1.0.4.jar;C:Program Files (x86)scalalibscala-reflect.jar;C:Program Files (x86)scalalibscala-swing_2.11-1.0.2.jar;C:Program Files (x86)scalalibscala-xml_2.11-1.0.4.jar" com.aura.scala.day01.forComprehensions
pan1
pan3
(1,9)
(2,8)
(3,7)
(4,6)
(5,5)