Will find and print recursively duplicated files in some dirs (comparison based on fileName + Size)

Dedup.kt

package fr.sdaclin.dedup

import java.io.File

/**
 * Will find recursively duplicated files in some dirs (comparison based on fileName + Size)
 */
fun main(args: Array<String>) {
    println("I'm working...")

    findDuplicates(File("/firstDir"), File("/optionalSecondDir"))
        .forEach {
            val listDuplicated = it.value.joinToString(prefix = "\n\t", separator = "\n\t") { it.file.absolutePath }
            println("${it.key}" + listDuplicated)
        }
}

fun findDuplicates(vararg dirToProceed: File): Map<String, List<DupFile>> {
    return dirToProceed.fold(emptySequence<File>()) { acc, file ->
        acc + file
            .walkTopDown()
            .filter { it.isFile }
    }
        .map { DupFile(it, it.name, it.length()) }
        .groupBy { it.name + "-" + it.size }
        .filter { it.value.size > 1 }
}

class DupFile(val file: File, val name: String, val size: Long)