https://www.reddit.com/r/scala/comments/5gpujf/preloading_code_snippets_in_the_ammonite_repl_you/
https://gist.github.com/lihaoyi/1ebdd89b065a741a1ea72b5d780b9ab1

lihaoyi Ammonite$ amm
Loading...
Welcome to the Ammonite Repl 0.8.0
(Scala 2.11.8 Java 1.8.0_112)
@ {
  val funnyFilter = ammonite.terminal.Filter.simple(" ")((b, c, m) =>
    if (FunnyFrontEnd.nextLine == Nil) (b.take(c) ++ " " ++ b.drop(c), c+1)
    else {
      val head :: tail = FunnyFrontEnd.nextLine
      FunnyFrontEnd.nextReader = new java.io.StringReader(head)
      FunnyFrontEnd.nextLine = tail
      (b, c)
    }
  )
  object FunnyFrontEnd extends  ammonite.repl.AmmoniteFrontEnd(funnyFilter){
    var nextLine = List.empty[String]
    var nextReader = new java.io.StringReader("")
    def setNextLines(s: Seq[String]) = nextLine = s.toList
    override def readLine(reader: java.io.Reader,
                 output: java.io.OutputStream,
                 prompt: String,
                 colors: ammonite.util.Colors,
                 compilerComplete: (Int, String) => (Int, Seq[String], Seq[String]),
                 history: IndexedSeq[String]) = {
      val readerX = new java.io.Reader{
        def close() = {reader.close(); nextReader.close()}
        def read(cbuf: Array[Char], off: Int, len: Int) = {
          val preRead = nextReader.read(cbuf, off, len)
          if(preRead == len) preRead
          else{
            val preReadNum = math.max(0, preRead)
            val postRead = reader.read(cbuf, off + preReadNum, len - preReadNum)
            if (postRead == -1) -1 else postRead + preReadNum
          }
        }
      }
      super.readLine(readerX, output, prompt, colors, compilerComplete, history)
    }
  }
  repl.frontEnd() = FunnyFrontEnd
  }
funnyFilter: AnyRef with ammonite.terminal.Filter{def op(ti: ammonite.terminal.TermInfo): Option[ammonite.terminal.TermState]} = $sess.cmd0.funnyFilter:1
defined object FunnyFrontEnd
@ FunnyFrontEnd.setNextLines(Seq("println(\"Hello\")", "println(\"World\")"))

@ println("Hello")
Hello

@ println("World")
World