Hello, World
Let us jump into the simplest possible Rust program, a classic Hello World program:
fn main() { println!("Hello 🌍!"); }
What you see:
- Functions are introduced with
fn
. - The
main
function is the entry point of the program. - Blocks are delimited by curly braces like in C and C++.
- Statements end with
;
. println
is a macro, indicated by the!
in the invocation.- Rust strings are UTF-8 encoded and can contain any Unicode character.
This slide tries to make the students comfortable with Rust code. They will see a ton of it over the next four days so we start small with something familiar.
Key points:
-
Rust is very much like other languages in the C/C++/Java tradition. It is imperative and it doesn’t try to reinvent things unless absolutely necessary.
-
Rust is modern with full support for Unicode.
-
Rust uses macros for situations where you want to have a variable number of arguments (no function overloading).
-
println!
is a macro because it needs to handle an arbitrary number of arguments based on the format string, which can’t be done with a regular function. Otherwise it can be treated like a regular function. -
Rust is multi-paradigm. For example, it has powerful object-oriented programming features, and, while it is not a functional language, it includes a range of functional concepts.