| layout | title | partof | overview-name | num | permalink |
|---|---|---|---|---|---|
multipage-overview | Programmatic Use of Scala REPL | repl | REPL | 2 | /overviews/repl/:title.html |
The REPL can be embedded and invoked programmatically.
It supports the javax.script API, or it can be used as either a code interpreter or an interactive command line.
import scala.tools.nsc.Settings import scala.tools.nsc.interpreter._ import javax.script._ /** A simple example showing programmatic usage of the REPL. */ object Main extends App { // the REPL has some support for javax.script val scripter = new ScriptEngineManager().getEngineByName("scala") scripter.eval("""println("hello, world")""") // compiler settings val settings = new Settings settings.processArgumentString("-deprecation -feature -Xfatal-warnings -Xlint") // the interpreter is used by the javax.script engine val intp = new IMain(settings) def interpret(code: String): Unit = { import Results._ val res = intp.interpret(code) match { case Success => "OK!" case _ => "Sorry, try again." } println(res) } interpret("""println("hello, world")""") interpret("""println(""") interpret("""val who = "world" ; println("hello, $who")""") // the REPL uses a line reader and an interpreter interactively val interactive = new ILoop() interactive.process(settings) // input to the REPL can be provided programmatically import java.io.{BufferedReader, StringReader, PrintWriter} val reader = new BufferedReader(new StringReader(""""hello, world"""")) val canned = new ILoop(reader, new PrintWriter(Console.out, true)) canned.process(settings) // more canning val code = """println("hello, world") ; 42""" val out = ILoop.run(code) println(s"Output is $out") } 