I’m not saying that there’s a problem with doing things one way or another. Rather, I’m asking whether there’s a problem with doing things differently that then led to this design decision to be made with Rust. I want to better understand how this language came to be.

The term “meta-programming” had me lost since I’m only familiar with that in reference to C++ templates (and Rust’s generics are more like templates).

Yes, like C++ template and macros. The kind of code that generates new code before being run.

So to answer your question as to why there are macros, it’s because you need to generate code based on the input. A function call can’t do that.

You can design a language where you don’t need to generate code to accomplish this. My question isn’t why this is necessary in Rust. My question is why Rust was designed such that this was necessary.

Someone mentioned elsewhere that this allows for compile-time type safety. I’m still trying to wrap my head around how that works.

I can see that. I’m coming in from the other extreme that is Python, where even the meta-programming is done in plain Python.

C++ was my first programming language. I remember the nightmare of dealing with dependencies and avoiding boost because it felt wrong to need a third part library for basic features. The toolchain for Rust is very nice (not just compared to C++, but all other languages I’ve worked with) and has so far been a huge joy to work with. The language itself too. I’m just curious about why the language likes to expose more of its features through meta-programming rather than directly in the language itself. Things like println! and format! being macros instead of functions, or needing a bunch of #[derive(Debug,Default,Eq,PartialEq)] everywhere for things that other language provide through regular code.

I’m not talking about what features are in the standard libraries vs third party libraries. I mean meta-programming as in the stuff that generates Rust code. Take console printing for example, we use a macro println! in Rust. Other languages provide an actual function (e.g. printf in C, System.out.println in Java, print in Python, etc). The code for my first project is also full of things like #[derive(Debug,Default,Eq,PartialEq)] to get features that I normally achieve through regular code in other languages. These things are still in the Rust standard library as I understand it.