added examples of closures

Author: pvdrz

src/liballoc/str.rs

@@ -959,13 +959,15 @@ impl str {
     /// assert_eq!(s.find("Léopard"), Some(13));
     /// ```
     ///
-    /// More complex patterns with closures:
+    /// More complex patterns using point-free style and closures:
     ///
     /// ```
     /// let s = "Löwe 老虎 Léopard";
     ///
     /// assert_eq!(s.find(char::is_whitespace), Some(5));
     /// assert_eq!(s.find(char::is_lowercase), Some(1));
+    /// assert_eq!(s.find(|c: char| c.is_whitespace()), Some(5));
+    /// assert_eq!(s.find(|c: char| c.is_lowercase()), Some(1));
     /// ```
     ///
     /// Not finding the pattern: