lecture 3 stuff

lectures/03/pair.rs

@@ -0,0 +1,31 @@
+struct Pair<I> {
+    iter: I
+}
+
+impl<I> Pair<I> {
+    fn new(iter: I) -> Self {
+        Self {
+            iter
+        }
+    }
+}
+
+impl<I: Iterator> Iterator for Pair<I> {
+    type Item = (I::Item, I::Item);
+
+    fn next(&mut self) -> Option<Self::Item> {
+       Some((self.iter.next()?, self.iter.next()?))
+    }
+}
+
+use std::collections::HashMap;
+
+fn main() {
+    let v = vec!["homer", "25", "bart", "55", "monty", "101"];
+    let h: HashMap<_, _> = Pair::new(v.into_iter()).filter_map(|(c, s)| 
+        match s.parse::<u8>() {
+            Ok(score) if score <= 100 => Some((c, score)),
+            _ => None,
+        }).collect();
+    println!("{h:?}");
+}