Merge pull request #2294 from senekor/senekor/qxykzqyxnnwy

Remove use of `map` in early vecs2 exercise

Author: mo8it

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## Unreleased
 
+### Changed
+
+- `vecs2`: Removed the use of `map` and `collect`, which are only taught later.
+
 ## 6.5.0 (2025-08-21)
 
 ### Added

exercises/05_vecs/vecs2.rs

@@ -9,26 +9,6 @@ fn vec_loop(input: &[i32]) -> Vec<i32> {
     output
 }
 
-fn vec_map_example(input: &[i32]) -> Vec<i32> {
-    // An example of collecting a vector after mapping.
-    // We map each element of the `input` slice to its value plus 1.
-    // If the input is `[1, 2, 3]`, the output is `[2, 3, 4]`.
-    input.iter().map(|element| element + 1).collect()
-}
-
-fn vec_map(input: &[i32]) -> Vec<i32> {
-    // TODO: Here, we also want to multiply each element in the `input` slice
-    // by 2, but with iterator mapping instead of manually pushing into an empty
-    // vector.
-    // See the example in the function `vec_map_example` above.
-    input
-        .iter()
-        .map(|element| {
-            // ???
-        })
-        .collect()
-}
-
 fn main() {
     // You can optionally experiment here.
 }
@@ -43,18 +23,4 @@ mod tests {
         let ans = vec_loop(&input);
         assert_eq!(ans, [4, 8, 12, 16, 20]);
     }
-
-    #[test]
-    fn test_vec_map_example() {
-        let input = [1, 2, 3];
-        let ans = vec_map_example(&input);
-        assert_eq!(ans, [2, 3, 4]);
-    }
-
-    #[test]
-    fn test_vec_map() {
-        let input = [2, 4, 6, 8, 10];
-        let ans = vec_map(&input);
-        assert_eq!(ans, [4, 8, 12, 16, 20]);
-    }
 }

rustlings-macros/info.toml

@@ -318,16 +318,7 @@ of the Rust book to learn more."""
 name = "vecs2"
 dir = "05_vecs"
 hint = """
-In the first function, we create an empty vector and want to push new elements
-to it.
-
-In the second function, we map the values of the input and collect them into
-a vector.
-
-After you've completed both functions, decide for yourself which approach you
-like better.
-
-What do you think is the more commonly used pattern under Rust developers?"""
+Use the `.push()` method on the vector to push new elements to it."""
 
 # MOVE SEMANTICS
 

solutions/05_vecs/vecs2.rs

@@ -8,22 +8,6 @@ fn vec_loop(input: &[i32]) -> Vec<i32> {
     output
 }
 
-fn vec_map_example(input: &[i32]) -> Vec<i32> {
-    // An example of collecting a vector after mapping.
-    // We map each element of the `input` slice to its value plus 1.
-    // If the input is `[1, 2, 3]`, the output is `[2, 3, 4]`.
-    input.iter().map(|element| element + 1).collect()
-}
-
-fn vec_map(input: &[i32]) -> Vec<i32> {
-    // We will dive deeper into iterators, but for now, this is all what you
-    // had to do!
-    // Advanced note: This method is more efficient because it automatically
-    // preallocates enough capacity. This can be done manually in `vec_loop`
-    // using `Vec::with_capacity(input.len())` instead of `Vec::new()`.
-    input.iter().map(|element| 2 * element).collect()
-}
-
 fn main() {
     // You can optionally experiment here.
 }
@@ -38,18 +22,4 @@ mod tests {
         let ans = vec_loop(&input);
         assert_eq!(ans, [4, 8, 12, 16, 20]);
     }
-
-    #[test]
-    fn test_vec_map_example() {
-        let input = [1, 2, 3];
-        let ans = vec_map_example(&input);
-        assert_eq!(ans, [2, 3, 4]);
-    }
-
-    #[test]
-    fn test_vec_map() {
-        let input = [2, 4, 6, 8, 10];
-        let ans = vec_map(&input);
-        assert_eq!(ans, [4, 8, 12, 16, 20]);
-    }
 }