A brief report on the current status and the perspectives of the SubScript language development as of April 2016.

1. SubScript: A Process
Algebra extension
progress and perspectives
Anatolii Kmetiuk
Andre van Delft

2. Plan
• Introduction of the language
• Examples and features available
• Future development

3. Introduction of the
language

4. Meet SubScript
• An extension to Scala programming language
• Adds a syntax for process description inspired by
the Algebra of Communicating Processes
• Aims for simplification of event-driven and
concurrent programming

5. Brief history
• Started as a library (VM), then the syntax was added by a compiler fork - it was difficult to
get started
• Developed into a preprocessor based on parser combinators to specify the syntax. It is
managed by an SBT plugin - easy to get started and play with the syntax
scalaVersion := "2.11.7"
libraryDependencies += "org.subscript-lang" %% "subscript-swing" % "3.0.3"
SubscriptSbt.projectSettings
addSbtPlugin("org.subscript-lang" %% "subscript-sbt-plugin" % "3.0.3")
build.sbt
project/build.sbt

6. Examples and
features available

7. Example: Hello World
import subscript.language
import subscript._
import subscript.Predef._
object Main extends SubScriptApplication {
script live = println("Hello") println("World")
}
Short
Verbose import subscript.language
import subscript._
import subscript.Predef._
object Main {
def main(args: Array[String]): Unit = runScript(live)
script live = {:println("Hello"):} {:println("World"):}
}

8. Operators
• Sequential: space, line break, “;” - identical
• Parallel: &&, &, ||, | - behaviour inspired by Boolean logic
• Choice: “+” operator selects between its operands
• Disruption: “/“ - left hand side disrupted by the right
hand side
• Conditional: if-then-else (boolean script result values as
a predicate), do-then-else (script success status as a
predicate)

9. Data Flow
• Each script can have a result value, it can be set
with a special syntax
• The result value can be processed using the
dataflow notation
script..
live = msg ~~(message: String)~~> println(message)
msg = ^"Hello World"

10. Example application: Eye Test
object Main extends SubScriptApplication {
script..
live = initGui
[ new WaitScreen || initData^ ]~~(repos: Repositories)~~>
[ new MainScreen(repos); let repos.close()]
initGui = javax.swing.UIManager.setLookAndFeel:
"com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel"
initData = ^{*new DerbyRepo("eyetest-db")*}
}

11. Example application: Eye Test
class Test extends Frame with FrameProcess {
script..
live = mainTestProcess^ / cancelBtn
mainTestProcess = eyeTest("Right")^^1
eyeTest("Left" )^^2
eyeTest(eyeName: String) = let testArea.font = new Font("Ariel", ..., 20)
let testArea.text = s"Look with $eyeName eye, OK when ready"
let answerField.enabled = false
sleep: 250
Key.Enter + okBtn
doTest( if(eyeName=="Right") previousScoreRight
else previousScoreLeft )^
}

12. Future development

13. Perspective directions
• User-computer interactions specification
• Prototyping & implementing the behaviour of consumer electronics:
TV, cooking plates, ...
• Simulation & verification: railroad interlocking
• SubScriptJS: run in web browser; improve NodeJS
• Preprocessor: ScalaParse & Dotty

14. https://github.com/scala-subscript/koans
Getting Started: Koans

15. Getting Started: Cheat Sheet
https://www.cheatography.com/anatoliykmetyuk/cheat-sheets/subscript/

16. Getting Started: Homepage
• GitHub:
https://github.com/scala-subscript/subscript
• Official website: http://subscript-lang.org/

17. Thank you for your
attention!