How to convert a string from a text input into a function in a Scala

Question

I am creating a GUI using Scala which should play a signal dependent on the algorithm but into the textField, eg. sin(2*Pi*400*t). The playing function works perfectly, however

Answer 1

You want to compile the line of code that the user enters, with some useful preamble.

I haven't done this so I don't have a snippet handy (but try searching), but you can embed the REPL, have it compile the line of code, and then extract the result.

Here is a snippet that uses ILoop to get some output, but you want to use IMain to get a result with the result class that wraps the user function.

import scala.tools.nsc.interpreter.ILoop
import java.io.StringReader
import java.io.StringWriter
import java.io.PrintWriter
import java.io.BufferedReader
import scala.tools.nsc.Settings

object FuncRunner extends App {

  val line = "sin(2 * Pi * 400 * t)"

  val lines = """import scala.math._
    |var t = 1""".stripMargin

  val in = new StringReader(lines + "\n" + line + "\nval f = (t: Int) => " + line)
  val out = new StringWriter

  val settings = new Settings

  val looper = new ILoop(new BufferedReader(in), new PrintWriter(out))
  val res = looper process settings
  Console println s"[$res] $out"
}