We want to have a go at some type-checking, so the first step is to write some code that causes a type error. We are going for let x: i32 = 3.0;. To do that, we need to be able to lex and parse the : i32 part...

More info: https://artificialworlds.net/blog/2025/02/14/mini-rust-in-rust-015-parse-typed-assignment