How I currently access the REPL's interpreter

AccessToTheREPLInterpreter.kt

val context: Context = Context()
context.getService(ObjectService::class.java).addObject(scene)
context.getService(ObjectService::class.java).addObject(deferredRenderer)

interpreter = InterpreterWindow(context)
interpreter?.isVisible = true

/* some other init stuff */

/* here's what I want to do -- access the REPL's interpreter, feed it a file,
   and have that accessible in the REPL. This does not work with context.getService(ScriptService.class).run(...),
   as it seems to launch an own interpreter decoupled from the REPL's (which makes sense).
   I changed the InterpreterWindow's code such that it exposes a function `getREPL()`, so
   the interpreter becomes accessible. From InterpreterWindow, the REPL is accessible, as
   InterpreterPane exposes it.
*/   
val startup = Scanner(DeferredLightingRenderer::class.java.getResourceAsStream("startup.js"), "UTF-8").useDelimiter("\\A").next()
interpreter?.repl?.interpreter?.eval(startup)