Replacing Nested Maps with Tuple Keys in Java and Kotlin

We at Appxiom built a simple but useful library for Java and Kotlin. AxTuple (ax-tuple-java) is a MIT Licensed lightweight library available as Maven library and Gradle plugin. Let's try AxTuple in a real-world scenario where we have a deeply nested HashMap structure. The goal is simple: reduce complexity without introducing unnecessary DTOs. AxTuple is extremely practical for flattening multi-layer maps into clean, readable composite keys — while remaining immutable and safe to use in hash-based collections. In this post, I’ll walk through: The problem with nested maps The clean alternative using Tuple When to use NamedTuple instead Java and Kotlin examples Practical observations after testing The Problem: Nested HashMap Let’s say we are tracking feature usage in an application. We want to count how many times a feature is used based on: Environment ( prod , staging ) Region ( us-east , eu-west ) Feature name ( dark_mode , search_v2 ) The naive structure looks like this: Map < String