PersonalNameKonad.kt

data class PersonalName(
    val firstname: NotEmptyString,
    val middleInitial: NotEmptyString?,
    val lastname: NotEmptyString){

    companion object {
        fun of(firstname: String, lastname: String, middleInitial: String? = null): Result<PersonalName> =
            ::PersonalName.curry()
                .on(NotEmptyString.of(firstname))
                .on(middleInitial?.run { NotEmptyString.of(middleInitial) } ?: null.ok())
                .on(NotEmptyString.of(lastname))
                .result
    }
}

when(val nameResult = PersonalName.of("Foo", "", "")){
    is Result.Ok -> nameResult.value.toString()
    is Result.Errors -> nameResult.description("\n")
}.run(::println)