Comments.

Coverage to Makefile.toml.

Added branch to map! to allow for instantiating with default values.

src/vector/distinct.rs

@@ -1,4 +1,6 @@
+/// Modify self to contain only distinct elements.
 pub trait Distinct {
+    /// Modify self to contain only distinct elements.
     fn distinct(&mut self);
 }
 

src/vector/map.rs

@@ -1,6 +1,38 @@
+/// Create a `HashMap` with the given key-value pairs.
+/// There are three ways to use this macro:
+/// 1. `map!()`: Create an empty `HashMap`.
+/// 2. `map!(usize; 1, 2)`: Create a `HashMap` with the keys `1` and `2` with the default value of `usize`.
+/// 3. `map!("one" => 1, "two" => 2)`: Create a `HashMap` with the keys `"one"` and `"two"` with the values `1` and `2` respectively.
+/// # Examples
+/// ```
+/// use std::collections::HashMap;
+///
+/// let empty_map: HashMap<usize, usize> = lib::map!();
+/// assert_eq!(empty_map.len(), 0);
+///
+/// let map: HashMap<&str, usize> = lib::map!("one" => 1, "two" => 2);
+/// assert_eq!(map.len(), 2);
+/// assert_eq!(map.get("one"), Some(&1));
+/// assert_eq!(map.get("two"), Some(&2));
+///
+/// let map: HashMap<usize, usize> = lib::map!(usize; 1, 2);
+/// assert_eq!(map.len(), 2);
+/// assert_eq!(map.get(&1), Some(&0));
+/// assert_eq!(map.get(&2), Some(&0));
+/// ```
 #[macro_export]
 macro_rules! map {
     () => { std::collections::HashMap::new() };
+    ($default:ty; $($key:expr),* $(,)?) => {
+        {
+            #[allow(unused_mut)]
+            let mut temp_map = std::collections::HashMap::new();
+            $(
+                temp_map.insert($key, <$default>::default());
+            )*
+            temp_map
+        }
+    };
     ($($k:expr => $v:expr),* $(,)?) => {
         {
             let mut temp_map = std::collections::HashMap::new();
@@ -33,4 +65,19 @@ mod tests {
         assert_eq!(map.get("two"), Some(&2));
         assert_eq!(map.get("three"), Some(&3));
     }
+
+    #[test]
+    fn test_map_only_keys() {
+        let map: HashMap<usize, usize> = map!(usize; 1, 2, 3);
+        assert_eq!(map.len(), 3);
+        assert_eq!(map.get(&1), Some(&0));
+        assert_eq!(map.get(&2), Some(&0));
+        assert_eq!(map.get(&3), Some(&0));
+    }
+
+    #[test]
+    fn test_map_only_keys_0_keys() {
+        let map: HashMap<usize, usize> = map!(usize;);
+        assert_eq!(map.len(), 0);
+    }
 }