The Complete Rust Programming Reference Guide

Wrap up

Hash maps are a great data structure, and often their value cannot be overstated, especially in caching or to simplify code that would otherwise have to match labels (or keys) to values using array indices. Their key breaking points are the hash function itself, and the bucket selection and organization, all of which warrant entire PhD theses and papers in computer science.

While a hash map is quick and easy to implement, the real question is: how does it perform? This is a valid question! Software engineers are prone to prefer their own implementation over learning what others already created, and while this is the premise for this entire book, benchmarks keep us honest and help us to appreciate the work that others have done.