Github repo: https://github.com/caveofprogramming/rust
If Let
If you just want to get one value out of an enum, you can use the if let statement
.The println here only executes if value is set to Some, and not None.
After if let we write a pattern describing the thing we’re looking for. I’ve given it a variable name number here, which we can then use if it successfully matches.
This can also be used as an expression, in which case we have to supply an else, to cover all possibilities.
Packages and Crates
The Rust docs say a crate is a unit of code. So main.rs is a crate.
Crates can contain modules.
A crate can be a binary crate or a library crate.
Binary crates compile to programs and must have a main.
Library crates don’t have a main and are libraries of code.
The crate root is a source file providing the starting point for the compiler, for example main.rs.
A package is a bundle of crates and contains a Cargo.toml.
A package can contain more than one binary crate but only one library crate.