Merge pull request #146 from rust-lang-ja/update_original_20230602

Update original

Author: dalance

.examples-en

@@ -41,7 +41,7 @@ fn main() {
 ## Stringの解析
 
 <!--
-One of the more common types to convert a string into is a number. The idiomatic
+One of the more common types to convert a string into a number. The idiomatic
 approach to this is to use the [`parse`] function and either to arrange for
 type inference or to specify the type to parse using the 'turbofish' syntax.
 Both alternatives are shown in the following example.

src/conversion/string.md

@@ -8,6 +8,8 @@ Let's create a library, and then see how to link it to another crate.
 -->
 ではライブラリを作成し、それを別のクレートにリンクする方法を見ていきましょう。
 
+In `rary.rs`:
+
 ```rust,ignore
 pub fn public_function() {
     println!("called rary's `public_function()`");

src/crates/lib.md

@@ -11,7 +11,7 @@ error:
 以前の例では`parse`の呼び出しに対するその場での対応として、エラーをライブラリのエラーからboxされたエラーへと`map`していました。
 
 ```rust,ignore
-.and_then(|s| s.parse::<i32>()
+.and_then(|s| s.parse::<i32>())
     .map_err(|e| e.into())
 ```
 

src/error/multiple_error_types/reenter_question_mark.md

@@ -15,11 +15,11 @@ known in some languages as flatmap, comes in.
 `and_then()`は引数として与えられた関数にラップされた値を渡しますが、その値が`None`だった場合は`None`を返します。
 
 <!--
-In the following example, `cookable_v2()` results in an `Option<Food>`. 
+In the following example, `cookable_v3()` results in an `Option<Food>`. 
 Using `map()` instead of `and_then()` would have given an 
 `Option<Option<Food>>`, which is an invalid type for `eat()`.
 -->
-以下の例では`cookable_v2()`は`Option<Food>`を返すため、`and_then()`ではなく`map()`を使用すると最終的に`Option<Option<Food>>`になります。これは`eat()`には不適切な型です。
+以下の例では`cookable_v3()`は`Option<Food>`を返すため、`and_then()`ではなく`map()`を使用すると最終的に`Option<Option<Food>>`になります。これは`eat()`には不適切な型です。
 
 ```rust,editable
 #![allow(dead_code)]
@@ -52,21 +52,24 @@ fn have_recipe(food: Food) -> Option<Food> {
 fn cookable_v1(food: Food) -> Option<Food> {
     match have_recipe(food) {
         None       => None,
-        Some(food) => match have_ingredients(food) {
-            None       => None,
-            Some(food) => Some(food),
-        },
+        Some(food) => have_ingredients(food),
     }
 }
 
 // This can conveniently be rewritten more compactly with `and_then()`:
 // `and_then()`を用いることで、同じことをよりコンパクトに表現できる。
-fn cookable_v2(food: Food) -> Option<Food> {
+fn cookable_v3(food: Food) -> Option<Food> {
     have_recipe(food).and_then(have_ingredients)
 }
 
+// Otherwise we'd need to `flatten()` an `Option<Option<Food>>`
+// to get an `Option<Food>`:
+fn cookable_v2(food: Food) -> Option<Food> {
+    have_recipe(food).map(have_ingredients).flatten()
+}
+
 fn eat(food: Food, day: Day) {
-    match cookable_v2(food) {
+    match cookable_v3(food) {
         Some(food) => println!("Yay! On {:?} we get to eat {:?}.", day, food),
         None       => println!("Oh no. We don't get to eat on {:?}?", day),
     }
@@ -87,10 +90,10 @@ fn main() {
 ### 参照
 
 <!--
-[closures][closures], [`Option`][option], and [`Option::and_then()`][and_then]
 -->
-[closures][closures], [`Option`][option], [`Option::and_then()`][and_then]
+[closures][closures], [`Option`][option], [`Option::and_then()`][and_then], and [`Option::flatten()`][flatten]
 
 [closures]: ../../fn/closures.md
 [option]: https://doc.rust-lang.org/std/option/enum.Option.html
 [and_then]: https://doc.rust-lang.org/std/option/enum.Option.html#method.and_then
+[flatten]: https://doc.rust-lang.org/std/option/enum.Option.html#method.flatten

src/error/option_unwrap/and_then.md

@@ -74,10 +74,10 @@ use std::num::ParseIntError;
 
 // As with `Option`, we can use combinators such as `map()`.
 // This function is otherwise identical to the one above and reads:
-// Modify n if the value is valid, otherwise pass on the error.
+// Multiply if both values can be parsed from str, otherwise pass on the error.
 // `Option`と同様、`map()`などのコンビネータを使うことができます。
 // この関数は`map()`を使っている点以外は上記の関数と同じで、
-// 値が有効ならnを変更し、無効であればエラーをそのまま見送ります。
+// 両方の値がstrからパース可能であればそれらを乗算し、無効であればエラーをそのまま見送ります。
 fn multiply(first_number_str: &str, second_number_str: &str) -> Result<i32, ParseIntError> {
     first_number_str.parse::<i32>().and_then(|first_number| {
         second_number_str.parse::<i32>().map(|second_number| first_number * second_number)

src/error/result/result_map.md

@@ -2,6 +2,9 @@
 
 
 > 🛈 stable since: rust 1.65
+>
+> 🛈 you can target specific edition by compiling like this
+> `rustc --edition=2021 main.rs`
 
 
 With `let`-`else`, a refutable pattern can match and bind variables
@@ -22,7 +25,9 @@ fn get_count_item(s: &str) -> (u64, &str) {
     (count, item)
 }
 
-assert_eq!(get_count_item("3 chairs"), (3, "chairs"));
+fn main() {
+    assert_eq!(get_count_item("3 chairs"), (3, "chairs"));
+}
 ```
 
 The scope of name bindings is the main thing that makes this different from
@@ -57,4 +62,4 @@ patterns with an unfortunate bit of repetition and an outer `let`:
 [match]: ./match.md
 [if_let]: ./if_let.md
 [let_else_rfc]: https://rust-lang.github.io/rfcs/3137-let-else.html
-[option]: ../std/option.md
+[option]: ../std/option.md

src/flow_control/let_else.md

@@ -35,6 +35,12 @@ fn main() {
         // `x`に言及していないため、以下はエラーになる。
         //Foo { y } => println!("y = {}", y),
     }
+
+    let faa = Foo { x: (1, 2), y: 3 };
+
+    // You do not need a match block to destructure structs:
+    let Foo { x : x0, y: y0 } = faa;
+    println!("Outside: x0 = {x0:?}, y0 = {y0}");
 }
 ```
 

src/flow_control/match/destructuring/destructure_structures.md

@@ -9,6 +9,7 @@ A `match` *guard* can be added to filter the arm.
 `match`内の条件文をフィルタリングするために、 *ガード(`guard`)* を使用することができます。
 
 ```rust,editable
+#[allow(dead_code)]
 enum Temperature {
     Celsius(i32),
     Fahrenheit(i32),

src/flow_control/match/guard.md

@@ -81,10 +81,10 @@ fn main() {
     let _triangle = Triangle  { length: 3.0, height: 4.0 };
 
     print_debug(&rectangle);
-    println!("Area: {}", rectangle.area());
+    println!("Area: {}", area(&rectangle));
 
     //print_debug(&_triangle);
-    //println!("Area: {}", _triangle.area());
+    //println!("Area: {}", area(&_triangle));
     // ^ TODO: Try uncommenting these.
     // | Error: Does not implement either `Debug` or `HasArea`. 
     // ^ TODO: これらの行をアンコメントしてみましょう。