Module kotlin-stdlib

Kotlin Standard Library

The Kotlin Standard Library provides living essentials for everyday work with Kotlin. These include:

  • Higher-order functions implementing idiomatic patterns ([let][kotlin.let], [apply][kotlin.apply], [use][kotlin.io.use], [synchronized][kotlin.synchronized], etc).
  • Extension functions providing querying operations for collections (eager) and sequences (lazy).
  • Various utilities for working with strings and char sequences.
  • Extensions for JDK classes making it convenient to work with files, IO, and threading.

Package kotlin

Core functions and types, available on all supported platforms.

Package kotlin.annotation

Library support for the Kotlin annotation facility.

Package kotlin.browser

Access to top-level properties (document, window etc.) in the browser environment.

Package kotlin.collections

Collection types, such as [Iterable][kotlin.collections.Iterable], [Collection][kotlin.collections.Collection], [List][kotlin.collections.List], [Set][kotlin.collections.Set], [Map][kotlin.collections.Map] and related top-level and extension functions.

Package kotlin.comparisons

Helper functions for creating [Comparator][kotlin.Comparator] instances.

Package kotlin.concurrent

Utility functions for concurrent programming.

Package kotlin.contracts

Experimental DSL for declaring custom function contracts.

Package kotlin.coroutines

Basic primitives for creating and suspending coroutines: [Continuation][kotlin.coroutines.Continuation], [CoroutineContext][kotlin.coroutines.CoroutineContext] interfaces, coroutine creation and suspension top-level functions.

Package kotlin.coroutines.intrinsics

Low-level building blocks for libraries that provide coroutine-based APIs.

Package kotlin.coroutines.cancellation

Provides exceptions arising on suspended coroutine cancellation.

Package kotlin.dom

Utility functions for working with the browser DOM.

Package kotlin.enums

Utilities for working with Kotlin enum classes.

Package kotlin.experimental

Experimental APIs, subject to change in future versions of Kotlin.

Package kotlin.io

IO API for working with files and streams.

Package kotlin.io.path

Convenient extensions for working with file system using [java.nio.file.Path][java.nio.file.Path].

Package kotlin.io.encoding

API for encoding and decoding data using various encoding schemes, such as [Base64][kotlin.io.encoding.Base64].

Package kotlin.js

Functions and other APIs specific to the JavaScript platform.

Package kotlin.js.collections

JavaScript-specific collection types, such as [JsArray][kotlin.js.collections.JsArray] and [JsReadonlyMap][kotlin.js.collections.JsReadonlyMap].

Package kotlin.jvm

Functions and annotations specific to the Java platform.

Package kotlin.jvm.optionals

Convenience extension functions for java.util.Optional to simplify Kotlin-Java interop.

Package kotlin.math

Mathematical functions and constants.

The functions include trigonometric, hyperbolic, exponentiation and power, logarithmic, rounding, sign and absolute value.

Package kotlin.native

Provides functions and types specific to Kotlin/Native, as well as means for interoperability with an underlying platform and other languages.

Package kotlin.native.concurrent

Kotlin/Native-specific concurrency primitives and utility functions for concurrent programming.

Package kotlin.native.ref

API for object life-cycle and references management.

Package kotlin.native.runtime

Allows to query information from and interact with the Kotlin/Native runtime.

Package kotlin.properties

Standard implementations of delegates for delegated properties and helper functions for implementing custom delegates.

Package kotlin.random

Provides the default generator of pseudo-random values, the repeatable generator, and a base class for other RNG implementations.

Package kotlin.ranges

Ranges, Progressions and related top-level and extension functions.

Package kotlin.reflect

Runtime API for Kotlin reflection

Package kotlin.reflect.full

Extensions for Kotlin reflection provided by kotlin-reflect library.

Package kotlin.reflect.jvm

Runtime API for interoperability between Kotlin reflection and Java reflection provided by kotlin-reflect library.

Package kotlin.sequences

[Sequence][kotlin.sequences.Sequence] type that represents lazily evaluated collections. Top-level functions for instantiating sequences and extension functions for sequences.

Classification of sequences

The sequence operations can be classified into the following groups regarding their state requirements:

  • stateless – operations which require no state and process each element independently like [kotlin.sequences.Sequence.map], [kotlin.sequences.Sequence.filter], or require a small constant amount of state to process an element, for example [kotlin.sequences.Sequence.take] or [kotlin.sequences.Sequence.drop];
  • stateful – operations which require a significant amount of state, usually proportional to the number of elements in a sequence.

If the sequence operation returns another sequence, which is produced lazily, it's called intermediate, and otherwise the operation is terminal. Examples of terminal operations are [kotlin.sequences.Sequence.toList], [kotlin.sequences.Sequence.max].

Sequences can be iterated multiple times, however some sequence implementations might constrain themselves to be iterated only once. That is mentioned specifically in their documentation (e.g. [kotlin.sequences.generateSequence] overload). The latter sequences throw an exception on an attempt to iterate them the second time.

Package kotlin.streams

Utility functions for working with Java 8 streams.

Package kotlin.system

System-related utility functions.

Package kotlin.test

Functions for writing test assertions.

Package kotlin.text

Functions for working with text and regular expressions.

Package kotlin.time

API for measuring time intervals and calculating durations.

For more information, see our Time measurement guide.

Package kotlin.uuid

Multiplatform Uuid class and utility functions for working with UUIDs.

Package kotlinx.cinterop

Experimental API for working with unmanaged and foreign memory, as well as for interoperability with other languages, such as Objective-C and C.

Package org.khronos.webgl

Kotlin JavaScript wrappers for the WebGL API.

Package org.w3c.dom

Kotlin JavaScript wrappers for the DOM API.

Package org.w3c.dom.css

Kotlin JavaScript wrappers for the DOM CSS API.

Package org.w3c.dom.events

Kotlin JavaScript wrappers for the DOM events API.

Package org.w3c.dom.parsing

Kotlin JavaScript wrappers for the DOM parsing API.

Package org.w3c.dom.svg

Kotlin JavaScript wrappers for the DOM SVG API.

Package org.w3c.dom.url

Kotlin JavaScript wrappers for the DOM URL API.

Package org.w3c.fetch

Kotlin JavaScript wrappers for the W3C fetch API.

Package org.w3c.files

Kotlin JavaScript wrappers for the W3C file API.

Package org.w3c.notifications

Kotlin JavaScript wrappers for the Web Notifications API.

Package org.w3c.performance

Kotlin JavaScript wrappers for the Navigation Timing API.

Package org.w3c.workers

Kotlin JavaScript wrappers for the Web Workers API.

Package org.w3c.xhr

Kotlin JavaScript wrappers for the XMLHttpRequest API.