Spawning VIM

spawn_vim.scala

import cats.effect._
import cats.implicits._

import java.io.PrintWriter
import java.nio.file.Path

object Editor {
  type Editor = String

  sealed trait EditorError

  final case class EditorNotSet(message: String = "The EDITOR environment variable is not set!")
    extends Exception(message) with EditorError

  private val get: IO[Editor] = IO.fromEither(sys.env.get("EDITOR").toRight(EditorNotSet()))

  private def spawnEditor(path: Path)(editor: Editor): IO[(ExitCode, Path)] =
    IO.blocking {
      val process = Runtime.getRuntime.exec("/bin/bash", null, null)
      val printWriter: PrintWriter = new java.io.PrintWriter(process.getOutputStream) {
        println(s"$editor $path < /dev/tty > /dev/tty")
        close()
      }

      process.waitFor()
    }.map(exitCode => (ExitCode(exitCode), path))

  val spawn: Path => IO[(ExitCode, Path)] =
    path => get >>= spawnEditor(path)
}

// Usage (returns IO (blocking))
Editor.spawn(Path.of("/tmp/test.md"))