diff --git a/bin/diffutils/params.rs b/bin/diffutils/params.rs
index 1c0dcf1..9c1517a 100644
--- a/bin/diffutils/params.rs
+++ b/bin/diffutils/params.rs
@@ -33,7 +33,7 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
     let exe = match opts.next() {
         Some(from) => from,
         None => {
-            return Err(format!("Usage: <exe> <from> <to>"));
+            return Err("Usage: <exe> <from> <to>".to_string());
         }
     };
     let mut from = None;
@@ -55,8 +55,8 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
             continue;
         }
         let p = osstr_bytes(&param);
-        if p.get(0) == Some(&b'-') && p.get(1) != Some(&b'-') {
-            let mut bit = p[1..].into_iter().copied().peekable();
+        if p.first() == Some(&b'-') && p.get(1) != Some(&b'-') {
+            let mut bit = p[1..].iter().copied().peekable();
             // Can't use a for loop because `diff -30u` is supposed to make a diff
             // with 30 lines of context.
             while let Some(b) = bit.next() {
@@ -64,31 +64,31 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
                     b'0'..=b'9' => {
                         context_count = (b - b'0') as usize;
                         while let Some(b'0'..=b'9') = bit.peek() {
-                            context_count = context_count * 10;
+                            context_count *= 10;
                             context_count += (bit.next().unwrap() - b'0') as usize;
                         }
                     }
                     b'c' => {
                         if format.is_some() && format != Some(Format::Context) {
-                            return Err(format!("Conflicting output style options"));
+                            return Err("Conflicting output style options".to_string());
                         }
                         format = Some(Format::Context);
                     }
                     b'e' => {
                         if format.is_some() && format != Some(Format::Ed) {
-                            return Err(format!("Conflicting output style options"));
+                            return Err("Conflicting output style options".to_string());
                         }
                         format = Some(Format::Ed);
                     }
                     b'u' => {
                         if format.is_some() && format != Some(Format::Unified) {
-                            return Err(format!("Conflicting output style options"));
+                            return Err("Conflicting output style options".to_string());
                         }
                         format = Some(Format::Unified);
                     }
                     b'U' => {
                         if format.is_some() && format != Some(Format::Unified) {
-                            return Err(format!("Conflicting output style options"));
+                            return Err("Conflicting output style options".to_string());
                         }
                         format = Some(Format::Unified);
                         let context_count_maybe = if bit.peek().is_some() {
@@ -102,7 +102,7 @@ pub fn parse_params<I: IntoIterator<Item = OsString>>(opts: I) -> Result<Params,
                             context_count = context_count_maybe;
                             break;
                         } else {
-                            return Err(format!("Invalid context count"));
+                            return Err("Invalid context count".to_string());
                         }
                     }
                     _ => return Err(format!("Unknown option: {}", String::from_utf8_lossy(&[b]))),
diff --git a/lib/context-diff/src/lib.rs b/lib/context-diff/src/lib.rs
index 4974c8d..38eee45 100644
--- a/lib/context-diff/src/lib.rs
+++ b/lib/context-diff/src/lib.rs
@@ -1,6 +1,6 @@
 use std::collections::VecDeque;
 use std::io::Write;
-use std::mem;
+
 
 #[derive(Debug, PartialEq)]
 pub enum DiffLine {
@@ -106,7 +106,7 @@ fn make_diff(expected: &[u8], actual: &[u8], context_size: usize) -> Vec<Mismatc
                 if let Some(DiffLine::Add(content)) =
                     mismatch.expected.get_mut(expected_lines_change_idx)
                 {
-                    let content = mem::replace(content, Vec::new());
+                    let content = std::mem::take(content);
                     mismatch.expected[expected_lines_change_idx] = DiffLine::Change(content);
                     expected_lines_change_idx = expected_lines_change_idx.wrapping_sub(1); // if 0, becomes !0
                     mismatch.actual.push(DiffLine::Change(str.to_vec()));
@@ -192,7 +192,7 @@ fn make_diff(expected: &[u8], actual: &[u8], context_size: usize) -> Vec<Mismatc
     results.push(mismatch);
     results.remove(0);
 
-    if results.len() == 0 && expected_lines_count != actual_lines_count {
+    if results.is_empty() && expected_lines_count != actual_lines_count {
         let mut mismatch = Mismatch::new(expected_lines.len(), actual_lines.len());
         // empty diff and only expected lines has a missing line at end
         if expected_lines_count != expected_lines.len() {
@@ -230,19 +230,15 @@ fn make_diff(expected: &[u8], actual: &[u8], context_size: usize) -> Vec<Mismatc
 
     // hunks with pure context lines get truncated to empty
     for mismatch in &mut results {
-        if mismatch
+        if !mismatch
             .expected
-            .iter()
-            .find(|x| !matches!(x, DiffLine::Context(_)))
-            .is_none()
+            .iter().any(|x| !matches!(&x, DiffLine::Context(_)))
         {
             mismatch.expected_all_context = true;
         }
-        if mismatch
+        if !mismatch
             .actual
-            .iter()
-            .find(|x| !matches!(x, DiffLine::Context(_)))
-            .is_none()
+            .iter().any(|x| !matches!(&x, DiffLine::Context(_)))
         {
             mismatch.actual_all_context = true;
         }
@@ -261,7 +257,7 @@ pub fn diff(
     let mut output =
         format!("*** {}\t\n--- {}\t\n", expected_filename, actual_filename).into_bytes();
     let diff_results = make_diff(expected, actual, context_size);
-    if diff_results.len() == 0 {
+    if diff_results.is_empty() {
         return Vec::new();
     };
     for result in diff_results {
diff --git a/lib/ed-diff/src/lib.rs b/lib/ed-diff/src/lib.rs
index 7bc8b2c..f83e2d1 100644
--- a/lib/ed-diff/src/lib.rs
+++ b/lib/ed-diff/src/lib.rs
@@ -48,8 +48,8 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Result<Vec<Mismatch>, DiffError>
 
     debug_assert_eq!(b"".split(|&c| c == b'\n').count(), 1);
     // ^ means that underflow here is impossible
-    let expected_lines_count = expected_lines.len() - 1;
-    let actual_lines_count = actual_lines.len() - 1;
+    let _expected_lines_count = expected_lines.len() - 1;
+    let _actual_lines_count = actual_lines.len() - 1;
 
     if expected_lines.last() == Some(&&b""[..]) {
         expected_lines.pop();
@@ -66,7 +66,7 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Result<Vec<Mismatch>, DiffError>
     for result in diff::slice(&expected_lines, &actual_lines) {
         match result {
             diff::Result::Left(str) => {
-                if mismatch.actual.len() != 0 {
+                if !mismatch.actual.is_empty() {
                     results.push(mismatch);
                     mismatch = Mismatch::new(line_number_expected, line_number_actual);
                 }
@@ -77,10 +77,10 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Result<Vec<Mismatch>, DiffError>
                 mismatch.actual.push(str.to_vec());
                 line_number_actual += 1;
             }
-            diff::Result::Both(str, _) => {
+            diff::Result::Both(_str, _) => {
                 line_number_expected += 1;
                 line_number_actual += 1;
-                if mismatch.actual.len() != 0 || mismatch.expected.len() != 0 {
+                if !mismatch.actual.is_empty() || !mismatch.expected.is_empty() {
                     results.push(mismatch);
                     mismatch = Mismatch::new(line_number_expected, line_number_actual);
                 } else {
@@ -91,7 +91,7 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Result<Vec<Mismatch>, DiffError>
         }
     }
 
-    if mismatch.actual.len() != 0 || mismatch.expected.len() != 0 {
+    if !mismatch.actual.is_empty() || !mismatch.expected.is_empty() {
         results.push(mismatch);
     }
 
@@ -104,7 +104,7 @@ pub fn diff(expected: &[u8], actual: &[u8]) -> Result<Vec<u8>, DiffError> {
     let mut lines_offset = 0;
     for result in diff_results {
         let line_number_expected: isize = result.line_number_expected as isize + lines_offset;
-        let line_number_actual: isize = result.line_number_actual as isize + lines_offset;
+        let _line_number_actual: isize = result.line_number_actual as isize + lines_offset;
         let expected_count: isize = result.expected.len() as isize;
         let actual_count: isize = result.actual.len() as isize;
         match (expected_count, actual_count) {
@@ -137,13 +137,13 @@ pub fn diff(expected: &[u8], actual: &[u8]) -> Result<Vec<u8>, DiffError> {
                     writeln!(&mut output, "..\n.\ns/.//\na").unwrap();
                 } else {
                     output.write_all(actual).unwrap();
-                    writeln!(&mut output, "").unwrap();
+                    writeln!(&mut output).unwrap();
                 }
             }
             writeln!(&mut output, ".").unwrap();
         }
     }
-    return Ok(output)
+    Ok(output)
 }
 
 pub fn diff_w(expected: &[u8], actual: &[u8], filename: &str) -> Result<Vec<u8>, DiffError> {
diff --git a/lib/normal-diff/src/lib.rs b/lib/normal-diff/src/lib.rs
index 14ee175..5b5d5bc 100644
--- a/lib/normal-diff/src/lib.rs
+++ b/lib/normal-diff/src/lib.rs
@@ -49,7 +49,7 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Vec<Mismatch> {
     for result in diff::slice(&expected_lines, &actual_lines) {
         match result {
             diff::Result::Left(str) => {
-                if mismatch.actual.len() != 0 && !mismatch.actual_missing_nl {
+                if !mismatch.actual.is_empty() && !mismatch.actual_missing_nl {
                     results.push(mismatch);
                     mismatch = Mismatch::new(line_number_expected, line_number_actual);
                 }
@@ -81,7 +81,7 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Vec<Mismatch> {
                     (true, true) | (false, false) => {
                         line_number_expected += 1;
                         line_number_actual += 1;
-                        if mismatch.actual.len() != 0 || mismatch.expected.len() != 0 {
+                        if !mismatch.actual.is_empty() || !mismatch.expected.is_empty() {
                             results.push(mismatch);
                             mismatch = Mismatch::new(line_number_expected, line_number_actual);
                         } else {
@@ -94,7 +94,7 @@ fn make_diff(expected: &[u8], actual: &[u8]) -> Vec<Mismatch> {
         }
     }
 
-    if mismatch.actual.len() != 0 || mismatch.expected.len() != 0 {
+    if !mismatch.actual.is_empty() || !mismatch.expected.is_empty() {
         results.push(mismatch);
     }
 
@@ -140,7 +140,7 @@ pub fn diff(expected: &[u8], actual: &[u8]) -> Vec<u8> {
         for expected in &result.expected {
             write!(&mut output, "< ").unwrap();
             output.write_all(expected).unwrap();
-            writeln!(&mut output, "").unwrap();
+            writeln!(&mut output).unwrap();
         }
         if result.expected_missing_nl {
             writeln!(&mut output, r"\ No newline at end of file").unwrap();
@@ -151,7 +151,7 @@ pub fn diff(expected: &[u8], actual: &[u8]) -> Vec<u8> {
         for actual in &result.actual {
             write!(&mut output, "> ").unwrap();
             output.write_all(actual).unwrap();
-            writeln!(&mut output, "").unwrap();
+            writeln!(&mut output).unwrap();
         }
         if result.actual_missing_nl {
             writeln!(&mut output, r"\ No newline at end of file").unwrap();
diff --git a/lib/unified-diff/src/lib.rs b/lib/unified-diff/src/lib.rs
index a9f29a1..0caecf5 100644
--- a/lib/unified-diff/src/lib.rs
+++ b/lib/unified-diff/src/lib.rs
@@ -180,7 +180,7 @@ fn make_diff(expected: &[u8], actual: &[u8], context_size: usize) -> Vec<Mismatc
     results.push(mismatch);
     results.remove(0);
 
-    if results.len() == 0 && expected_lines_count != actual_lines_count {
+    if results.is_empty() && expected_lines_count != actual_lines_count {
         let mut mismatch = Mismatch::new(expected_lines.len() as u32, actual_lines.len() as u32);
         // empty diff and only expected lines has a missing line at end
         if expected_lines_count != expected_lines.len() as u32 {
@@ -229,7 +229,7 @@ pub fn diff(
     let mut output =
         format!("--- {}\t\n+++ {}\t\n", expected_filename, actual_filename).into_bytes();
     let diff_results = make_diff(expected, actual, context_size);
-    if diff_results.len() == 0 {
+    if diff_results.is_empty() {
         return Vec::new();
     };
     for result in diff_results {