Creating things from scratch is still definitely a thing, particularly for high performance code. Sure, there are plenty of data structure libraries, but squeezing out that last bit of performance often requires something bespoke.
For example, I recently wrote a custom CSV parser because I needed something that did no heap allocation but without mutating the original character array (using explicit string lengths).
For example, I recently wrote a custom CSV parser because I needed something that did no heap allocation but without mutating the original character array (using explicit string lengths).