pods4k

Performance-oriented data structures for Kotlin

A collection of performance-oriented data structures providing performance and efficiency that might appear to be impossible at first glance.

If you find this library useful, please consider giving it a on GitHub and sharing it with others.

Dependency

Gradle:

dependencies {
    implementation("com.danrusu.pods4k:pods4k:0.6.0")
}

Maven:

<dependency>
    <groupId>com.danrusu.pods4k</groupId>
    <artifactId>pods4k</artifactId>
    <version>0.6.0</version>
</dependency>

Alternatively, you can pick & choose individual components of this library.

Immutable Arrays

Immutable Arrays offer a safer and more efficient alternative to lists while maintaining the same look and feel.

Key Benefits

• Clean & Familiar
  • Uses a list-like syntax ensuring easy adoption with clean code.
• True Immutability
  • Unlike read-only lists, Immutable Arrays cannot be mutated through casting.
• Fast
  • 2 to 8 times faster than lists for many common operations, with some even faster!
• Memory Efficient
  • Over 5X memory reduction versus lists for many common scenarios!
    • people.map { it.weightKg } creates a primitive ImmutableFloatArray.
  • Many operations retain zero extra memory when results are empty or the same elements.
    • people.filter { it.isEmployed() } returns same instance when everyone is employed.
  • etc.
• Type Safety
  • Accidental mutation attempts are prevented at compile time.

Usage

val people = immutableArrayOf(dan, jill, bobby)
people[0] // dan

// Normal iteration with loops, forEach, asSequence, etc.
for (person in people) {
    sendMarketingEmail(person)
}

// All the typical transformations and conditions
val adults = people.filter { it.age >= 18 }
val adultAges = adults.map { it.age }
val containsRetirees = adults.any { it.isRetired() }

See Immutable Arrays for more specifics along with benchmarks and detailed comparisons against regular arrays, read-only lists, and immutable lists.

Minimum Requirements

• Kotlin 1.9.25
  • This library is K2 compatible as it's used in other projects that use Kotlin 2.1 etc.
• JDK 11
  • Automated tests are run on JDK LTS releases 11, 17, & 21

Java Compatibility

Some data structures use techniques which are only supported by the Kotlin compiler. While they can be used in a mixed Java & Kotlin codebase to store one of these data structures in a Java-defined collection, referencing these data structures by their class name is only supported within Kotlin files.