Shocks

Weird Rust stuff documented.

There is no null in Rust!

Instead, there is None, and there is:
```
enum Option<T>{
   Some(T),
   None
}
```
String AsRef<Path>

Why the heck String has a responsibility for Path...
Why Rust doesn't allow marking only some struct fields mutable?

Each field is in a different memory location. However, the struct is a type. So, when using it, we can't know which part of the struct's instance that the other code is going to use.

I couldn't grasp how to run multiple files together from get-go

src/main.rs:

   mod vectors;
   fn main() {
       vectors::run_vectors();
   }

src/vectors.rs:

   pub fn run_vectors() {
       println!("vectors!");
   }

👉 See this for the best explanation.

String concatenation uses the buffer of the origin string

This is a good thing as in the op below, Rust will copy str2 to str1's buffer.
```
let str3 = str1 + &str2;
```
People can add their own hashers to stdlib's HashMap implementation

Check out them here.