I built a small Redis clone in C: a RESP parser, a command table, an append-only file for persistence. Recently I started building the same thing again in Rust, and rebuilding a project I had already finished has taught me more Rust than any from-scratch tutorial.
The reason is simple. The second time, the design is already solved. I know what the AOF has to guarantee, what the command table dispatches, what the parser must reject. So none of my attention goes to what to build. All of it goes to how Rust wants it built.
That turns the domain into a constant and the language into the only variable. Every difference I hit is pure signal about Rust, not noise about key-value stores.
The first difference shows up before any logic runs. In C, I built the substrate first: my own dynamic strings, my own hashmap, my own linked list. Hundreds of lines before a single command worked. In Rust, Vec, String, and HashMap are just there, so that whole layer disappears and I start at the actual command logic. A standard library quietly decides where your project even begins.
The sharper difference is in dispatch. In C it is a switch with argument counts I check by hand:
