Async updates and reformatting for new exercise

- Renamed/ordered the directories for macros, clippy, and conversions, shifting them all one up in numerical order to fit async as number 21
- Added the 21_async directories in exercises and solutions
- Added async1.rs in the 21_async directory in exercises and solutions
- Added async to the info.toml in rustlings-macros and reordered the rest of the exercises in there as well
- Created an exercise for async1 and its solution

exercises/21_async/README.md

@@ -0,0 +1,16 @@
+# Async (Asynchronous Programming)
+
+Asynchronous programming allows a program to perform tasks concurrently
+without blocking the main execution thread. It is particularly useful
+for I/O-bound operations, such as network requests or file reading,
+where waiting for a response can be done in the background.
+In Rust, asynchronous functions are defined using the async keyword
+and are executed with the help of an asynchronous runtime like tokio.
+This approach improves the efficiency and responsiveness of applications
+by enabling them to handle multiple tasks simultaneously.
+
+## Further information
+
+- [Asynchronous Programming in Rust](https://doc.rust-lang.org/book/ch17-00-async-await.html)
+- [Learn Tokio](https://tokio.rs/tokio/tutorial/)
+- [Tokio Documentation](https://docs.rs/tokio/latest/tokio/)

exercises/21_async/async1.rs

@@ -0,0 +1,34 @@
+// Modify delayed_hello to return the string "Hello, world!"
+// after waiting for 1 second to pass the test and fix the
+// compiler error.
+
+use tokio::time::{sleep, Duration};
+
+// TODO: Change the function signature to fix the compiler error
+fn delayed_hello() -> String {
+    // TODO: Return the string "Hello, world!" after waiting for 1 second
+    // ...
+
+    "Hello, world!".to_string()
+}
+
+#[tokio::main]
+async fn main() {
+    // You can experiment optionally here
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::time::Duration;
+
+    #[tokio::test]
+    async fn test_delayed_hello() {
+        let start = std::time::Instant::now();
+        let result = delayed_hello().await;
+        let duration = start.elapsed();
+        assert_eq!(result, "Hello, world!");
+        assert!(duration >= Duration::from_secs(1));
+        println!("Test passed!");
+    }
+}

rustlings-macros/info.toml

@@ -1079,11 +1079,27 @@ original sending end.
 Related section in The Book:
 https://doc.rust-lang.org/book/ch16-02-message-passing.html"""
 
+# ASYNC
+
+[[exercises]]
+name = "async1"
+dir = "21_async"
+hint = """
+Remember what keyword is used to define an asynchronous function. The function
+returns a `Future` that can be awaited.
+
+A keyword is used to wait for the result of a `Future`. It can only
+be used inside an asyncronous function.
+
+For documentation on 'tokio::sleep', see:
+https://docs.rs/tokio/latest/tokio/time/fn.sleep.html"""
+
+
 # MACROS
 
 [[exercises]]
 name = "macros1"
-dir = "21_macros"
+dir = "22_macros"
 test = false
 hint = """
 When you call a macro, you need to add something special compared to a regular
@@ -1091,7 +1107,7 @@ function call."""
 
 [[exercises]]
 name = "macros2"
-dir = "21_macros"
+dir = "22_macros"
 test = false
 hint = """
 Macros don't quite play by the same rules as the rest of Rust, in terms of
@@ -1102,7 +1118,7 @@ Unlike other things in Rust, the order of "where you define a macro" versus
 
 [[exercises]]
 name = "macros3"
-dir = "21_macros"
+dir = "22_macros"
 test = false
 hint = """
 In order to use a macro outside of its module, you need to do something
@@ -1110,7 +1126,7 @@ special to the module to lift the macro out into its parent."""
 
 [[exercises]]
 name = "macros4"
-dir = "21_macros"
+dir = "22_macros"
 test = false
 hint = """
 You only need to add a single character to make this compile.
@@ -1127,7 +1143,7 @@ https://veykril.github.io/tlborm/"""
 
 [[exercises]]
 name = "clippy1"
-dir = "22_clippy"
+dir = "23_clippy"
 test = false
 strict_clippy = true
 hint = """
@@ -1144,7 +1160,7 @@ appropriate replacement constant from `std::f32::consts`."""
 
 [[exercises]]
 name = "clippy2"
-dir = "22_clippy"
+dir = "23_clippy"
 test = false
 strict_clippy = true
 hint = """
@@ -1157,7 +1173,7 @@ https://doc.rust-lang.org/std/option/#iterating-over-option"""
 
 [[exercises]]
 name = "clippy3"
-dir = "22_clippy"
+dir = "23_clippy"
 test = false
 strict_clippy = true
 hint = "No hints this time!"
@@ -1166,20 +1182,20 @@ hint = "No hints this time!"
 
 [[exercises]]
 name = "using_as"
-dir = "23_conversions"
+dir = "24_conversions"
 hint = """
 Use the `as` operator to cast one of the operands in the last line of the
 `average` function into the expected return type."""
 
 [[exercises]]
 name = "from_into"
-dir = "23_conversions"
+dir = "24_conversions"
 hint = """
 Follow the steps provided right before the `From` implementation."""
 
 [[exercises]]
 name = "from_str"
-dir = "23_conversions"
+dir = "24_conversions"
 hint = """
 The implementation of `FromStr` should return an `Ok` with a `Person` object,
 or an `Err` with an error if the string is not valid.
@@ -1196,7 +1212,7 @@ https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reen
 
 [[exercises]]
 name = "try_from_into"
-dir = "23_conversions"
+dir = "24_conversions"
 hint = """
 Is there an implementation of `TryFrom` in the standard library that can both do
 the required integer conversion and check the range of the input?
@@ -1206,6 +1222,6 @@ types?"""
 
 [[exercises]]
 name = "as_ref_mut"
-dir = "23_conversions"
+dir = "24_conversions"
 hint = """
 Add `AsRef<str>` or `AsMut<u32>` as a trait bound to the functions."""

solutions/21_async/async1.rs

@@ -0,0 +1,30 @@
+use tokio::time::{sleep, Duration};
+
+// Change the function signature to be async and return a Future
+async fn delayed_hello() -> String {
+    // Wait for 1 second
+    sleep(Duration::from_secs(1)).await;
+
+    "Hello, world!".to_string()
+}
+
+#[tokio::main]
+async fn main() {
+    // You can experiment optionally here
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::time::Duration;
+
+    #[tokio::test]
+    async fn test_delayed_hello() {
+        let start = std::time::Instant::now();
+        let result = delayed_hello().await;
+        let duration = start.elapsed();
+        assert_eq!(result, "Hello, world!");
+        assert!(duration >= Duration::from_secs(1));
+        println!("Test passed!");
+    }
+}