generics1 rewrite and solution

exercises/14_generics/generics1.rs

@@ -1,7 +1,18 @@
-// This shopping list program isn't compiling! Use your knowledge of generics to
+// `Vec<T>` is generic over the type `T`. In most cases, the compiler is able to
-// fix it.
+// infer `T`, for example after pushing a value with a concrete type to the vector.
+// But in this exercise, the compiler needs some help through a type annotation.
 
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    // TODO: Fix the compiler error by annotating the type of the vector
-    shopping_list.push("milk");
+    // `Vec<T>`. Choose `T` as some integer type that can be created from
+    // `u8` and `i8`.
+    let mut numbers = Vec::new();
+
+    // Don't change the lines below.
+    let n1: u8 = 42;
+    numbers.push(n1.into());
+    let n2: i8 = -1;
+    numbers.push(n2.into());
+
+    println!("{numbers:?}");
 }

rustlings-macros/info.toml

@@ -734,8 +734,13 @@ test = false
 hint = """
 Vectors in Rust make use of generics to create dynamically sized arrays of any
 type.
+If the vector `numbers` has the type `Vec<T>`, then we can only push values of
+type `T` to it. By using `into()` before pushing, we ask the compiler to convert
+`n1` and `n2` to `T`. But the compiler doesn't know what `T` is yet and needs a
+type annotation.
 
-You need to tell the compiler what type we are pushing onto this vector."""
+`u8` and `i8` can both be converted to `i16`, `i32` and `i64`. Choose one for
+the generic of the vector."""
 
 [[exercises]]
 name = "generics2"

solutions/14_generics/generics1.rs

@@ -1 +1,17 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+// `Vec<T>` is generic over the type `T`. In most cases, the compiler is able to
+// infer `T`, for example after pushing a value with a concrete type to the vector.
+// But in this exercise, the compiler needs some help through a type annotation.
+
+fn main() {
+    // `u8` and `i8` can both be converted to `i16`.
+    let mut numbers: Vec<i16> = Vec::new();
+    //             ^^^^^^^^^^ added
+
+    // Don't change the lines below.
+    let n1: u8 = 42;
+    numbers.push(n1.into());
+    let n2: i8 = -1;
+    numbers.push(n2.into());
+
+    println!("{numbers:?}");
+}