How can we tell the compiler that we want x to be an int?

Rust has a way of informing both the compiler and the developer of the variable type. For example, for a 32-bit int, we would use the following:

let x = 1i32; 

In other words, x = 1, a 32-bit signed int.

If a variable is defined without the i32 (or any other value), the compiler will decide the type depending on how the value is used, defaulting to i32.