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Scala

Overview​

Scala is a powerful language that combines object-oriented and functional programming. Runner Codes provides Scala with OpenJDK runtime.

Specifications​

PropertyValue
Base OSDebian Bookworm
VersionScala 2.11
Rootfs Size900 MB
ExecutionCompiled (scalac + scala)
File Extension.scala
Compile Commandscalac Main.scala
Run Commandscala Main
Execution Time~3.9s
1. Create Rootfs with infra.operator
sudo infra.operator rootfs create --name scala --size 900 --base debian --packages "scala"
2. Create Snapshot
sudo infra.operator snapshot create --lang scala --mem 512 --vcpus 1
3. Upload rootfs to S3
sudo infra.operator rootfs upload --lang scala --bucket runner-codes
3. Upload snapshot to S3
sudo infra.operator snapshot upload --lang scala --bucket runner-codes
4. Test Execution
sudo infra.operator host --lang scala --code "object Main { def main(args: Array[String]): Unit = { println(\"Hello from Scala\") } }" --mem 512 --vcpus 1 --snapshot

Examples​

Hello World​

Request
{
  "trace_id": "scala-hello-001",
  "lang": "scala",
  "code": "object Main {\n  def main(args: Array[String]): Unit = {\n    println(\"Hello from Scala!\")\n  }\n}",
  "timeout": 45
}
Response
{
  "trace_id": "scala-hello-001",
  "stdout": "Hello from Scala!\n",
  "stderr": "",
  "exit_code": 0
}

Case Classes​

Request
{
  "trace_id": "scala-case-001",
  "lang": "scala",
  "code": "case class Person(name: String, age: Int)\n\nobject Main {\n  def main(args: Array[String]): Unit = {\n    val alice = Person(\"Alice\", 30)\n    println(s\"Name: ${alice.name}\")\n    println(s\"Age: ${alice.age}\")\n    println(alice)\n  }\n}",
  "timeout": 45
}
Response
{
  "trace_id": "scala-case-001",
  "stdout": "Name: Alice\nAge: 30\nPerson(Alice,30)\n",
  "stderr": "",
  "exit_code": 0
}

Pattern Matching​

Request
{
  "trace_id": "scala-match-001",
  "lang": "scala",
  "code": "object Main {\n  def main(args: Array[String]): Unit = {\n    val x: Any = 42\n    x match {\n      case i: Int => println(s\"Integer: $i\")\n      case s: String => println(s\"String: $s\")\n      case _ => println(\"Unknown\")\n    }\n  }\n}",
  "timeout": 45
}
Response
{
  "trace_id": "scala-match-001",
  "stdout": "Integer: 42\n",
  "stderr": "",
  "exit_code": 0
}

Collections​

Request
{
  "trace_id": "scala-coll-001",
  "lang": "scala",
  "code": "object Main {\n  def main(args: Array[String]): Unit = {\n    val numbers = List(1, 2, 3, 4, 5)\n    val squares = numbers.map(x => x * x)\n    val sum = squares.sum\n    \n    println(s\"Numbers: $numbers\")\n    println(s\"Squares: $squares\")\n    println(s\"Sum: $sum\")\n  }\n}",
  "timeout": 45
}
Response
{
  "trace_id": "scala-coll-001",
  "stdout": "Numbers: List(1, 2, 3, 4, 5)\nSquares: List(1, 4, 9, 16, 25)\nSum: 55\n",
  "stderr": "",
  "exit_code": 0
}

Higher-Order Functions​

Request
{
  "trace_id": "scala-hof-001",
  "lang": "scala",
  "code": "object Main {\n  def main(args: Array[String]): Unit = {\n    val numbers = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)\n    \n    val evens = numbers.filter(_ % 2 == 0)\n    val doubled = numbers.map(_ * 2)\n    val sum = numbers.reduce(_ + _)\n    \n    println(s\"Evens: $evens\")\n    println(s\"Doubled: $doubled\")\n    println(s\"Sum: $sum\")\n  }\n}",
  "timeout": 45
}
Response
{
  "trace_id": "scala-hof-001",
  "stdout": "Evens: List(2, 4, 6, 8, 10)\nDoubled: List(2, 4, 6, 8, 10, 12, 14, 16, 18, 20)\nSum: 55\n",
  "stderr": "",
  "exit_code": 0
}

Limitations​

warning

The Scala environment has the following limitations:

  1. Compilation overhead: scalac is slow (~3-4s)
  2. No external libraries: Only Scala standard library
  3. Memory limit: 512 MiB
  4. Increase timeout: Use 45+ seconds
  5. Main object required: Must have object Main with def main(args: Array[String])

Best Practices​

Best Practices
  • Name your object Main — Always name your main object Main for proper execution.
  • Use case classes — Case classes provide equals, hashCode, toString automatically.
  • Use pattern matching — Scala's pattern matching is powerful for handling data.
  • Account for compilation — Set timeout to at least 60 seconds for JVM startup.