Read from console / standard input

[tbagrel1]

Hello,
I didn't find a way to read from console (stdin of the current process) using os-lib.
I expected to find such a feature in a lib designed to handle OS interfacing (something like os.read.lines.stream(os.Stdin)).
In the Scala API doc, I only found how to manage standard input of subprocesses, not how to access the standard input of the current process and read from it.
Can you help me? Thanks!

[acloudmovingby]

Hi @tbagrel1,

I'm not a maintainer of this library but I stumbled upon your question.

Reading from stdin can be done with just basic Scala, in particular the methods on scala.io.Stdin such as Stdin.readLine().

---

Now your desire to have a "stream" of input is rather interesting actually. Here are a few options I can think of but I'm not sure any of them are optimal:

• while loop with mutable var
• LazyList
• 3rd party libraries like ZStreams

A while loop (not very "functional programming" but easily understood by most programmers):

var in: String = ""
while ({
	in = StdIn.readLine()
	in != "foo" // terminate loop if user enters "foo"
}) {
	// ...do whatever you want to do with `in`....
}

LazyList (standard Scala's concept of a lazy "stream") has various factory methods in its companion object. This is one of many ways you could skin this cat:

val inputStream: LazyList[String] = LazyList.continually(StdIn.readLine())
inputStream
	.takeWhile(_ != "foo") // end when user enters "foo"
	.map { line =>
		println(s"You entered: $line")
		line
	}
	.toList // You need this! Otherwise the LazyList will never start getting evaluated

I like ZIO ZStreams, but that's somewhat out of the scope of this question.