romanowski

Scala CLI live demo

1. Install Scala CLI - most likely with brew install Virtuslab/scala-cli/scala-cli

2. Create a project with library (greet.scala and app greeter.sc)

greet.scala:

def greet(name: String) = s"Hello, $name!"

romanowski

val numbers = Seq(1,2,3,5,7,42)

romanowski

{
  "scala-cli-sip": {
    "repositories": [
      "central"
    ],
    "name": "scala-cli-sip",
    "dependencies": [
      "org.virtuslab.scala-cli:cli_3:latest.release"
    ],
    "launcherType": "graalvm-native-image",

romanowski

// using scala 3.0.2
// using lib org.apache.spark:spark-sql_2.13:3.2.0

// using repository https://wip-repos.s3.eu-central-1.amazonaws.com/.release
// using lib io.github.vincenzobaz::spark-scala3:0.1.3-new-spark

import scala3encoders.given

import org.apache.spark.sql.Dataset
import org.apache.spark.sql.SparkSession

romanowski

// using scala 3

// using repository https://repository.apache.org/content/repositories/staging
// using org.apache.spark:spark-sql_2.13:3.2.0

// using repository https://wip-repos.s3.eu-central-1.amazonaws.com/.release
// using io.github.vincenzobaz::spark-scala3:0.1.3-new-spark

// using org.scala-lang::scala3-tasty-inspector:3.0.2
// using "io.get-coursier:coursier_2.13:2.0.16-169-g194ebc55c"

romanowski

object ScalaVersion extends App {
  def props(url: java.net.URL): java.util.Properties = {
    val properties = new java.util.Properties()
    val is = url.openStream()
    try {
      properties.load(is)
      properties
    } finally is.close()    
  }

romanowski

The mechanism to define tests in scala-cli should cover following usecases:

1. User should be able to define test file without any configuration
2. User should be able to define test directory within a global configuration file (e.g. config.scala)
3. User should be able to mark current file as tests

We've considered many ways how we can achieve that with @using directives however this introduced following problems:

• @using directictives content applies to the whole compilation unit but in case of tests we want to apply it to the current file. We can workaround this using following syntax @using tests.from thisFile or similar but it feels not natural and ovious.
• we feel that defining a constrains about build when file should be applied is conecptually different then providing setting that are compliation unit-wide

Our proposal is to create another directive called @target that will define contraints about target that this files applies to. We think that target should be define before any @usin

romanowski

class PlayerTraits(str : Int, dex : Int, wis : Int) {
  @CompilerControl(DONT_INLINE) def strCost: Int = str
  @CompilerControl(DONT_INLINE) def dexCost: Int = dex
  @CompilerControl(DONT_INLINE) def wisCost: Int = wis
}

romanowski

trait Mapper[A, B]{
    def map(a: Rep[B]): Rep[Option[A]]
  }
  object Mapper {
    implicit def plain[A: BaseTypedType] = new Mapper[A, A] { override def map(a: Rep[A]) = a.?}
    implicit def option[A] = new Mapper[A, Option[A]] { override def map(a: Rep[Option[A]]) = a}
  }
  trait Optionable[A]{
    type M[Original] = Mapper[A, Original]
  }

romanowski

package object lib {
  // When we make RicherString implicit class Foo won't compile
  class RicherString(base: String) {
    val head: Char = if(base.isEmpty) ' ' else base.charAt(0)
  }
}