Task

Write a program that will list everything in the current folder,   similar to:

   the Unix utility   “ls”   [1]       or 
   the Windows terminal command   “DIR” 


The output must be sorted, but printing extended details and producing multi-column output is not required.



Example output
For the list of paths:

/foo/bar
/foo/bar/1
/foo/bar/2
/foo/bar/a
/foo/bar/b



When the program is executed in   `/foo`,   it should print:

bar

and when the program is executed in   `/foo/bar`,   it should print:

1
2
a
b



// Version 1.2.41
 
import java.io.File
 
fun ls(directory: String) {
    val d = File(directory)
    if (!d.isDirectory) {
        println("$directory is not a directory")
        return
    }
    d.listFiles().map { it.name }
                 .sortedBy { it.toLowerCase() }  // case insensitive
                 .forEach { println(it) }
}
 
fun main(args: Array<String>) {
    ls(".")  // list files in current directory, say
}