another batch.

exercises/generics/generics1.rs

@@ -1,9 +1,7 @@
 // This shopping list program isn't compiling!
 // Use your knowledge of generics to fix it.
 
-// I AM NOT DONE
-
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }

exercises/generics/generics2.rs

@@ -1,14 +1,12 @@
 // This powerful wrapper provides the ability to store a positive integer value.
 // Rewrite it using generics so that it supports wrapping ANY type.
 
-// I AM NOT DONE
-
-struct Wrapper {
-    value: u32,
+struct Wrapper<T> {
+    value: T,
 }
 
-impl Wrapper {
-    pub fn new(value: u32) -> Self {
+impl<T> Wrapper<T> {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }

exercises/generics/generics3.rs

@@ -10,15 +10,15 @@
 
 // Execute 'rustlings hint generics3' for hints!
 
-// I AM NOT DONE
+use std::fmt::Display;
 
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T> where T: Display {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T: Display> ReportCard<T> {
     pub fn print(&self) -> String {
         format!("{} ({}) - achieved a grade of {}",
             &self.student_name, &self.student_age, &self.grade)
@@ -46,7 +46,7 @@ mod tests {
     fn generate_alphabetic_report_card() {
         // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+",
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };

exercises/option/option1.rs

@@ -1,23 +1,21 @@
 // option1.rs
 // Make me compile! Execute `rustlings hint option1` for hints
 
-// I AM NOT DONE
-
 // you can modify anything EXCEPT for this function's sig
 fn print_number(maybe_number: Option<u16>) {
     println!("printing: {}", maybe_number.unwrap());
 }
 
 fn main() {
-    print_number(13);
-    print_number(99);
+    print_number(Some(13));
+    print_number(Some(99));
 
-    let mut numbers: [Option<u16>; 5];
+    let mut numbers: [Option<u16>; 5] = [None; 5];
     for iter in 0..5 {
         let number_to_add: u16 = {
             ((iter * 1235) + 2) / (4 * 16)
         };
 
-        numbers[iter as usize] = number_to_add;
+        numbers[iter as usize] = Some(number_to_add);
     }
 }

exercises/option/option2.rs

@@ -1,12 +1,10 @@
 // option2.rs
 // Make me compile! Execute `rustlings hint option2` for hints
 
-// I AM NOT DONE
-
 fn main() {
     let optional_value = Some(String::from("rustlings"));
     // TODO: Make this an if let statement whose value is "Some" type
-    value = optional_value {
+    if let Some(value) = optional_value {
         println!("the value of optional value is: {}", value);
     } else {
         println!("The optional value doesn't contain anything!");
@@ -19,7 +17,7 @@ fn main() {
 
     // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
     // You can stack `Option<T>`'s into while let and if let
-    value = optional_values_vec.pop() {
+    while let Some(Some(value)) = optional_values_vec.pop() {
         println!("current value: {}", value);
     }
 }