Replace for loop with map

It seems cleaner to have two `map`s rather than a `for` loop iterating
over a `map`.

The two `map`s *could* be combined into one, but I think it's more
readable as two steps.

Author: camelid

ci/date-check/src/main.rs

@@ -49,26 +49,28 @@ fn make_date_regex() -> Regex {
 }
 
 fn collect_dates_from_file(date_regex: &Regex, text: &str) -> Vec<(usize, Date)> {
-    let mut dates = vec![];
     let mut line = 1;
     let mut end_of_last_cap = 0;
-    for (byte_range, date) in date_regex.captures_iter(&text).map(|cap| {
-        (
-            cap.get(0).unwrap().range(),
-            Date {
-                year: cap["y"].parse().unwrap(),
-                month: cap["m"].parse().unwrap(),
-            },
-        )
-    }) {
-        line += text[end_of_last_cap..byte_range.end]
-            .chars()
-            .filter(|c| *c == '\n')
-            .count();
-        dates.push((line, date));
-        end_of_last_cap = byte_range.end;
-    }
-    dates
+    date_regex
+        .captures_iter(&text)
+        .map(|cap| {
+            (
+                cap.get(0).unwrap().range(),
+                Date {
+                    year: cap["y"].parse().unwrap(),
+                    month: cap["m"].parse().unwrap(),
+                },
+            )
+        })
+        .map(|(byte_range, date)| {
+            line += text[end_of_last_cap..byte_range.end]
+                .chars()
+                .filter(|c| *c == '\n')
+                .count();
+            end_of_last_cap = byte_range.end;
+            (line, date)
+        })
+        .collect()
 }
 
 fn collect_dates(paths: impl Iterator<Item = PathBuf>) -> BTreeMap<PathBuf, Vec<(usize, Date)>> {