> It's not worth anyone's time to know how it works under the hood
Knowing (at a high level) how your programming language implements dictionaries has relevance to questions like time complexity of various operations, potential security vulnerabilities (a hash table might succumb to hash collision denial of service, especially if the implementation isn’t hardened against that possibility; a tree-based implementation probably won’t have that vulnerability), likely impact of different bugs (e.g. a buggy hash method can cause much more problems on a hash table than on a tree, while for a buggy comparison method it is the other way around), concurrency, etc
> because only a fool would actually implement one from scratch in production code
I’ve implemented a dictionary before in C. Not for work (only wrote C code for work one single time ever, and it was only a page worth of code that was called from Java, no complex data structures needed), just for my own learning/amusement. That said, C is probably the one context in which people still commonly “roll their own” basic data structures, even in production code, just because C’s standard library is so weak in that regard (and C’s lack of generics/templates doesn’t help either)
Knowing (at a high level) how your programming language implements dictionaries has relevance to questions like time complexity of various operations, potential security vulnerabilities (a hash table might succumb to hash collision denial of service, especially if the implementation isn’t hardened against that possibility; a tree-based implementation probably won’t have that vulnerability), likely impact of different bugs (e.g. a buggy hash method can cause much more problems on a hash table than on a tree, while for a buggy comparison method it is the other way around), concurrency, etc
> because only a fool would actually implement one from scratch in production code
I’ve implemented a dictionary before in C. Not for work (only wrote C code for work one single time ever, and it was only a page worth of code that was called from Java, no complex data structures needed), just for my own learning/amusement. That said, C is probably the one context in which people still commonly “roll their own” basic data structures, even in production code, just because C’s standard library is so weak in that regard (and C’s lack of generics/templates doesn’t help either)