Print Directory Tree with Groovy (with closure recursion)

While looking for a script that display directory tree, I came across this Groovy script.

The code look just fine but it don't work (I test it with Groovy 1.7). After some google, I found that this is due to the closure as a first class object in Groovy, it can't be call within the closure itself.

And below is the solution:

def listRecursivly

listRecursivly = { file, arg ->
    println "${'|  ' * arg}`- ${file.getName()}\\"
    file.eachFile() {f ->
        if(f.directory) {
            listRecursivly(f,(arg + 1))
        } else {
            println "${'|  ' * (arg + 1)}`- ${f.getName()}"
        }
    }
}

listRecursivly (new File("."),0)

The little trick here is to define and initialize the closure in 2 separate lines.