add final polish and fixup names, add comments

Author: miguelraz

exercise-solutions/iterators/src/bin/iterators1.rs

@@ -11,20 +11,21 @@ fn main() -> Result<(), Box<dyn Error>> {
     // Write your iterator chain here
     let sum_of_odd_numbers: i32 = reader.lines()
         .map(|l| l.unwrap())              // peel off each line from the BufReader until you're done
-        .map(|s| s.parse())               // try to parse the line as a number
-        .filter(|s| s.is_ok())            // keep the lines that actually parsed
+        .map(|s| s.parse())               // try to parse the line as a number, yields a `Result`
+        .filter(|s| s.is_ok())            // keep the lines that actually parsed (they're the `Ok` variant)
         .map(|l| l.unwrap())              // unwrap the succesful parses, which yield numbers
         .filter(|num| num % 2 != 0)       // keep the odd numbers
         .collect::<Vec<i32>>()            // collect the numbers into a vector
         .iter()                           // iterate over the vector
-        .fold(0, |acc, elem| acc + elem); // fold over the vector and add the elements
+        .fold(0, |acc, elem| acc + elem); // fold over the vector and add the elements, yields an i32
 
     assert_eq!(sum_of_odd_numbers, 31);
 
+    // Idiomatic solution
     let second_reader = BufReader::new(File::open("../exercise-solutions/iterators/numbers.txt")?);
     let nicer_sum: i32 = second_reader.lines()
-        .map(|l| l.unwrap())
-        .filter_map(|s| s.parse().ok())
+        .map(|l| l.unwrap())              
+        .filter_map(|s| s.parse().ok())   // map a .parse() and filter for the succesful parses
         .filter(|num| num % 2 != 0)
         .sum::<i32>();
 

exercise-templates/iterators/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [[bin]]
-name = "iter1"
-path = "src/bin/iter1.rs"
+name = "iterators1"
+path = "src/bin/iterators1.rs"
 
 [dependencies]