X-Git-Url: https://git.ralfj.de/rust-101.git/blobdiff_plain/a115b75de6e7e85f8799a77e2998ab1a24743e06..63b7a79069a399c32d575bb71832fcad134117c9:/src/part00.rs?ds=sidebyside diff --git a/src/part00.rs b/src/part00.rs index ed76e81..00eb4d1 100644 --- a/src/part00.rs +++ b/src/part00.rs @@ -35,10 +35,9 @@ fn vec_min(vec: Vec) -> NumberOrNothing { //@ immutable per default, and you need to tell Rust if you want //@ to change a variable later. - // Now we want to *iterate* over the list. Rust has some nice syntax for - // iterators: + // Now we want to *iterate* over the list. Rust has some nice syntax for iterators: for el in vec { - // So `el` is al element of the list. We need to update `min` accordingly, but how do we get the current + // So `el` is an element of the list. We need to update `min` accordingly, but how do we get the current // number in there? This is what pattern matching can do: match min { // In this case (*arm*) of the `match`, `min` is currently nothing, so let's just make it the number `el`. @@ -52,6 +51,8 @@ fn vec_min(vec: Vec) -> NumberOrNothing { min = NumberOrNothing::Number(new_min); /*@*/ } } + //@ Notice that Rust makes sure you did not forget to handle any case in your `match`. We say + //@ that the pattern matching has to be *exhaustive*. } // Finally, we return the result of the computation. return min; @@ -71,22 +72,21 @@ fn min_i32(a: i32, b: i32) -> i32 { // Indeed, we can: The following line tells Rust to take // the constructors of `NumberOrNothing` into the local namespace. -// Try moving that above the function, and removing all the occurrences `NumberOrNothing::`. +// Try moving that above the function, and removing all the occurrences of `NumberOrNothing::`. use self::NumberOrNothing::{Number,Nothing}; // To call this function, we now just need a list. Of course, ultimately we want to ask the user for // a list of numbers, but for now, let's just hard-code something. -//@ `vec!` is a *macro* (as you can tell from the `!`) that constructs a constant `Vec<_>` with the given +//@ `vec!` is a *macro* (as indicated by `!`) that constructs a constant `Vec<_>` with the given //@ elements. fn read_vec() -> Vec { vec![18,5,7,1,9,27] /*@*/ } -// Finally, let's call our functions and run the code! -// But, wait, we would like to actually see something, so we need to print the result. -// Of course Rust can print numbers, but after calling `vec_min`, we have a `NumberOrNothing`. -// So let's write a small helper function that prints such values. +// Of course, we would also like to actually see the result of the computation, so we need to print the result. +//@ Of course Rust can print numbers, but after calling `vec_min`, we have a `NumberOrNothing`. +//@ So let's write a small helper function that prints such values. //@ `println!` is again a macro, where the first argument is a *format string*. For //@ now, you just need to know that `{}` is the placeholder for a value, and that Rust @@ -105,11 +105,12 @@ pub fn main() { print_number_or_nothing(min); } -// You can now use `cargo build` to compile your code. If all goes well, try `cargo run` on the -// console to run it. +//@ You can now use `cargo build` to compile your *crate*. That's Rust's name for a *compilation unit*, which in +//@ the case of Rust means an application or a library.
+// Finally, try `cargo run` on the console to run it. //@ Yay, it said "1"! That's actually the right answer. Okay, we could have -//@ computed that ourselves, but that's besides the point. More importantly: +//@ computed that ourselves, but that's beside the point. More importantly: //@ You completed the first part of the course. -//@ [index](main.html) | previous | [next](part01.html) +//@ [index](main.html) | previous | [raw source](https://www.ralfj.de/git/rust-101.git/blob_plain/HEAD:/workspace/src/part00.rs) | [next](part01.html)