Kotlin in 2025: What's New for Beginners

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Kotlin in 2025: What's New for Beginners?

Kotlin has confidently secured its place among the top three fastest-growing programming languages. In 2025, it has become even more beginner-friendly while retaining its power for professionals. If you are just starting your programming journey or want to refresh your knowledge, this article is your guide to the most interesting innovations.

We will break down the key changes that make Kotlin in 2025 an ideal choice for a first language: improved syntax, new cross-platform development capabilities, enhanced tools for working with data, and much more.

1. Improved Syntax and Less Boilerplate Code

One of the main goals of the Kotlin team has always been to simplify writing code. In 2025, this is reflected in several important changes.

1.1. Smarter Type Inference

The compiler can now infer even complex types in lambdas and generic functions. This means you need to explicitly specify types less often, making the code cleaner and more readable.

// Kotlin 2025 — types are inferred automaticallyval numbers = listOf(1, 2, 3)val doubled = numbers.map { it * 2 } // Previously required .map { x: Int -> x * 2 }println(doubled) // [2, 4, 6]

1.2. New Syntactic Sugar for Collections

Built-in functions for working with collections have appeared, which previously required writing loops or chains of calls. For example, the chunkedBy method for splitting by condition.

val words = listOf("cat", "dog", "crocodile", "lion", "tiger")val grouped = words.chunkedBy { it.length } // new in 2025println(grouped) // [[cat], [dog], [crocodile], [lion, tiger]]

2. Kotlin Multiplatform (KMP) — Write Once, Run Everywhere

For beginner developers, this is a real breakthrough. In 2025, Kotlin Multiplatform has become stable and even easier to learn. You can write common code (logic, data models, network requests) once, and then use it on Android, iOS, Web, and Desktop.

2.1. Example of Common Code for Mobile Applications

Suppose you need to write a function for email validation. In 2025, you write it once in a common module:

// commonMain — common code for all platformsfun isValidEmail(email: String): Boolean {    return email.contains("@") && email.contains(".")}

This function is now available in both the Android app (in Kotlin) and the iOS app (via Swift/Kotlin Native). For a beginner, this means: learn one language — use it on all platforms.

2.2. Improved Integration with Compose Multiplatform

Jetpack Compose for Desktop and Web received many performance improvements in 2025. You can now create user interfaces in Kotlin that look native on all platforms. This is a great opportunity for beginners: no need to learn HTML/CSS for the web and SwiftUI for iOS — just one Kotlin is enough.

3. New Capabilities for Working with Data and AI

In 2025, Kotlin is actively entering the field of Data Science and machine learning. New libraries and improvements have appeared that make it accessible even to those who are not experts in mathematics.

3.1. Built-in DataFrame Support

The Kotlin DataFrame library has become part of the standard distribution. You can now analyze data without installing third-party dependencies. It's like Pandas in Python, but in Kotlin.

import org.jetbrains.kotlinx.dataframe.*

fun main() {    val df = dataFrameOf(        "name" to listOf("Alice", "Bob", "Charlie"),        "age" to listOf(25, 30, 35)    )    val filtered = df.filter { it["age"] > 28 }    println(filtered)    // Output: [Bob, 30], [Charlie, 35]}