class HashCacheProvider private constructor(private val dataFileLocation : Path) {

    private val hashCaches = mutableMapOf<LocalArchiveLocation, ArchiveHashCache>()

    companion object {
        fun invoke(dataFileLocation : Path) : IO<Either<Throwable, HashCacheProvider>> {
            return IO.fx {
                val (h) = IO { HashCacheProvider(dataFileLocation) }
                !effect { h.load() }
                h
            }.attempt()
        }
    }