Fabric-language-kotlin [patched] -

println("Loaded ${users.size} users")

// Custom serializer for LocalDateTime object LocalDateTimeSerializer : KSerializer<LocalDateTime> { override val descriptor = PrimitiveSerialDescriptor("LocalDateTime", PrimitiveKind.STRING) override fun serialize(encoder: Encoder, value: LocalDateTime) = encoder.encodeString(value.toString()) override fun deserialize(decoder: Decoder): LocalDateTime = LocalDateTime.parse(decoder.decodeString(), DateTimeFormatter.ISO_DATE_TIME) } fabric-language-kotlin

// 3. Last login recency val now = LocalDateTime.now() val avgDaysSinceLogin = users.mapNotNull { it.lastLogin } .map { ChronoUnit.DAYS.between(it, now) } .average() println("\nAverage days since last login: ${String.format("%.1f", avgDaysSinceLogin)}") println("Loaded ${users

Run:

val file = File("users.json") if (!file.exists()) { println("Error: users.json not found. Run generate_data.py first.") return } fabric-language-kotlin

Average days since last login: 6.2