From: Ralf Jung Date: Thu, 3 Sep 2015 01:52:06 +0000 (+0200) Subject: typos and wording (thanks, Thomas!) X-Git-Url: https://git.ralfj.de/rust-101.git/commitdiff_plain/8758d64fa600a64154978b245540e9e0c6af9db1?ds=sidebyside;hp=-c typos and wording (thanks, Thomas!) --- 8758d64fa600a64154978b245540e9e0c6af9db1 diff --git a/src/main.rs b/src/main.rs index e1e4a64..8fbc933 100644 --- a/src/main.rs +++ b/src/main.rs @@ -28,7 +28,9 @@ // a garbage collector) or vice versa. Rust can run without dynamic allocation (i.e., without // a heap), and even without an operating system. In fact, Rust rules out more classes of bugs // than languages that achieve safety with a garbage collector: Besides dangling pointers and -// double-free, Rust also prevents issues such as iterator invalidation and data races. +// double-free, Rust also prevents issues such as iterator invalidation and data races. Finally, +// it cleans up behind you, and deallocates resources (memory, but also file descriptors and really +// anything) when you don't need them anymore. // // // Getting started diff --git a/src/part00.rs b/src/part00.rs index 01d2046..00eb4d1 100644 --- a/src/part00.rs +++ b/src/part00.rs @@ -37,7 +37,7 @@ fn vec_min(vec: Vec) -> NumberOrNothing { // 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`. @@ -51,6 +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; @@ -70,13 +72,13 @@ 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] /*@*/ @@ -108,7 +110,7 @@ pub fn main() { // 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 | [raw source](https://www.ralfj.de/git/rust-101.git/blob_plain/HEAD:/workspace/src/part00.rs) | [next](part01.html) diff --git a/src/part01.rs b/src/part01.rs index 7d29c49..fa06a80 100644 --- a/src/part01.rs +++ b/src/part01.rs @@ -16,7 +16,7 @@ fn sqr(i: i32) -> i32 { i * i } //@ So we can just write `i * i`, the expression that returns the square if `i`! //@ This is very close to how mathematicians write down functions (but with more types). -// Conditionals are also just expressions. You can compare this to the ternary `? :` operator +// Conditionals are also just expressions. This is comparable to the ternary `? :` operator // from languages like C. fn abs(i: i32) -> i32 { if i >= 0 { i } else { -i } } @@ -45,7 +45,7 @@ fn compute_stuff(x: i32) -> i32 { fn vec_min(v: Vec) -> NumberOrNothing { //@ Remember that helper function `min_i32`? Rust allows us to define such helper functions *inside* other //@ functions. This is just a matter of namespacing, the inner function has no access to the data of the outer - //@ one. Still, being able to nicely group functions can be very useful. + //@ one. Still, being able to nicely group functions can significantly increase readability. fn min_i32(a: i32, b: i32) -> i32 { if a < b { a } else { b } /*@*/ } @@ -102,7 +102,7 @@ pub fn main() { // You will have to replace `part00` by `part01` in the `main` function in // `main.rs` to run this code. -// **Exercise 01.1**: Write a funtion `vec_sum` that computes the sum of all values of a `Vec`. +// **Exercise 01.1**: Write a function `vec_sum` that computes the sum of all values of a `Vec`. // **Exercise 01.2**: Write a function `vec_print` that takes a vector and prints all its elements. diff --git a/src/part02.rs b/src/part02.rs index 3be1cdd..a01081b 100644 --- a/src/part02.rs +++ b/src/part02.rs @@ -21,9 +21,9 @@ pub use self::SomethingOrNothing::*; //@ `SomethingOrNothing` to get back our `NumberOrNothing`. type NumberOrNothing = SomethingOrNothing; //@ However, we can also write `SomethingOrNothing` or even `SomethingOrNothing>`. -//@ In fact, such a type is so useful that it is already present in the standard library: It's called an +//@ In fact, a type like `SomethingOrNothing` is so useful that it is already present in the standard library: It's called an //@ *option type*, written `Option`. Go check out its [documentation](https://doc.rust-lang.org/stable/std/option/index.html)! -//@ (And don't worry, there's indeed lots of material mentioned there that we did not cover yet.) +//@ (And don't worry, there's indeed lots of material mentioned there that we have not covered yet.) // ## Generic `impl`, Static functions //@ The types are so similar, that we can provide a generic function to construct a `SomethingOrNothing` @@ -55,7 +55,7 @@ fn call_constructor(x: i32) -> SomethingOrNothing { } // ## Traits -//@ Now that we have a generic `SomethingOrNothing`, wouldn't it be nice to also gave a generic +//@ Now that we have a generic `SomethingOrNothing`, wouldn't it be nice to also have a generic //@ `vec_min`? Of course, we can't take the minimum of a vector of *any* type. It has to be a type //@ supporting a `min` operation. Rust calls such properties that we may demand of types *traits*. @@ -63,10 +63,10 @@ fn call_constructor(x: i32) -> SomethingOrNothing { //@ For now, just ignore the `Copy`, we will come back to this point later. //@ A `trait` is a lot like interfaces in Java: You define a bunch of functions //@ you want to have implemented, and their argument and return types.
-//@ The function `min` takes to arguments of the same type, but I made the +//@ The function `min` takes two arguments of the same type, but I made the //@ first argument the special `self` argument. I could, alternatively, have //@ made `min` a static function as follows: `fn min(a: Self, b: Self) -> Self`. -//@ However, in Rust one typically prefers methods over static function wherever possible. +//@ However, in Rust one typically prefers methods over static functions wherever possible. pub trait Minimum : Copy { fn min(self, b: Self) -> Self; } @@ -98,7 +98,7 @@ pub fn vec_min(v: Vec) -> SomethingOrNothing { //@ Before going on, take a moment to ponder the flexibility of Rust's take on abstraction: //@ We just defined our own, custom trait (interface), and then implemented that trait //@ *for an existing type*. With the hierarchical approach of, e.g., C++ or Java, -//@ that's not possible: We cannot make an existing type suddenly also inherit from our abstract base class. +//@ that's not possible: We cannot make an existing type also inherit from our abstract base class after the fact. //@ //@ In case you are worried about performance, note that Rust performs *monomorphisation* //@ of generic functions: When you call `vec_min` with `T` being `i32`, Rust essentially goes diff --git a/workspace/src/part00.rs b/workspace/src/part00.rs index 49e89eb..9144eae 100644 --- a/workspace/src/part00.rs +++ b/workspace/src/part00.rs @@ -17,7 +17,7 @@ fn vec_min(vec: Vec) -> NumberOrNothing { // 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`. @@ -48,7 +48,7 @@ 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 diff --git a/workspace/src/part01.rs b/workspace/src/part01.rs index ed6717c..be2c2d2 100644 --- a/workspace/src/part01.rs +++ b/workspace/src/part01.rs @@ -8,7 +8,7 @@ // ## Expression-based programming fn sqr(i: i32) -> i32 { i * i } -// Conditionals are also just expressions. You can compare this to the ternary `? :` operator +// Conditionals are also just expressions. This is comparable to the ternary `? :` operator // from languages like C. fn abs(i: i32) -> i32 { if i >= 0 { i } else { -i } } @@ -68,7 +68,7 @@ pub fn main() { // You will have to replace `part00` by `part01` in the `main` function in // `main.rs` to run this code. -// **Exercise 01.1**: Write a funtion `vec_sum` that computes the sum of all values of a `Vec`. +// **Exercise 01.1**: Write a function `vec_sum` that computes the sum of all values of a `Vec`. // **Exercise 01.2**: Write a function `vec_print` that takes a vector and prints all its elements.