If we were talking about the first person to discover monads, Wadler clearly would not be he. Wadler was but a wee toddler barely sputtering out his first words when the term "monad" was coined. As we are talking about who introduced monads to computer science, the signs I see continue to point to Wadler. His work is, by all appearances, what caught the attention of the computer science community. "Monads for functional programming" is regularly cited as the seminal paper. They are strongly associated with Haskell. It would even appear from the previous comment that you only came to learn about Moggi because of Wadler making his introduction, which echos Moggi not being particularly influential socially.

If you have evidence to suggest that Moggi played a bigger role in introducing (not inventing) the concepts, I am definitely keen to learn about it.

    qsort(base, nel, width, compar)
    char *base;
    int (*compar)();

These are all implementation details that shouldn't actually matter. What does matter is that the properties of your system are accounted for and validated. That goes in your test suite, or type system if your language has a sufficiently advanced type system.

If replacing Redis with an in-memory cache is a problem technically, your tests/compiler should prevent you from switching to an in-memory cache. If you don't have that, that is where you need to start. Once you have those tests/types, many of the questions will also get answered. It won't necessarily answer why Redis over Valkey, but it will demonstrate with clear intent why not an in-memory cache.