do not requite closures to be mutable

examples/arithmetic.rs

@@ -2,21 +2,19 @@ use clap::Parser;
 use rand::Rng;
 
 fn arithmetic(b: &plnk::Bencher) {
-    let mut rng = rand::thread_rng();
-
     plnk::bench(b, plnk::label! { operation: "addition" }, || {
-        let a = rng.gen::<u128>();
-        let b = rng.gen::<u128>();
+        let a = rand::thread_rng().gen::<u128>();
+        let b = rand::thread_rng().gen::<u128>();
         plnk::timeit(|| a + b)
     });
     plnk::bench(b, plnk::label! { operation: "substraction" }, || {
-        let a = rng.gen::<u128>();
-        let b = rng.gen::<u128>();
+        let a = rand::thread_rng().gen::<u128>();
+        let b = rand::thread_rng().gen::<u128>();
         plnk::timeit(|| a - b)
     });
     let res = plnk::bench_and_return(b, plnk::label! { operation: "multiplication" }, || {
-        let a = rng.gen::<u128>();
-        let b = rng.gen::<u128>();
+        let a = rand::thread_rng().gen::<u128>();
+        let b = rand::thread_rng().gen::<u128>();
         plnk::timeit_and_return(|| a * b)
     });
 
@@ -26,13 +24,13 @@ fn arithmetic(b: &plnk::Bencher) {
 fn arithmetic_multiple(b: &plnk::Bencher) {
     plnk::bench_multiple(
         b,
-        &mut [
+        vec![
             (
                 plnk::label! { operation: "addition" }.to_string(),
                 Box::new(|| {
                     let a = rand::thread_rng().gen::<u128>();
                     let b = rand::thread_rng().gen::<u128>();
-                    plnk::timeit(|| a + b)
+                    plnk::timeit(|| a - b)
                 }),
             ),
             (
@@ -56,9 +54,8 @@ fn arithmetic_multiple(b: &plnk::Bencher) {
 }
 
 fn random(b: &plnk::Bencher) {
-    let mut rng = rand::thread_rng();
     plnk::bench(b, plnk::label! { operation: "sampling" }, || {
-        plnk::timeit(|| rng.gen::<u128>())
+        plnk::timeit(|| rand::thread_rng().gen::<u128>())
     });
 }
 

src/lib.rs

@@ -65,9 +65,9 @@ macro_rules! label {
 /// same bencher
 /// - f: the piece of code to run and measure
 /// - the measurements will be printed to STDOUT as JSON
-pub fn bench<F>(b: &Bencher, label: &str, mut f: F)
+pub fn bench<F>(b: &Bencher, label: &str, f: F)
 where
-    F: FnMut() -> Duration,
+    F: Fn() -> Duration,
 {
     if !b.quiet {
         eprintln!("bencher: {}, label: {}", b.name, label);
@@ -93,7 +93,7 @@ where
 ///     - f: the piece of code to run and measure
 /// - the measurements will be printed to STDOUT as JSON
 #[allow(clippy::type_complexity)]
-pub fn bench_multiple(b: &Bencher, benches: &mut [(String, Box<dyn FnMut() -> Duration>)]) {
+pub fn bench_multiple(b: &Bencher, benches: Vec<(String, Box<dyn Fn() -> Duration>)>) {
     let style = ProgressStyle::with_template(
         "[{elapsed_precise}] {bar:40.cyan/blue} {pos:>10}/{len:10} {msg}",
     )
@@ -105,7 +105,7 @@ pub fn bench_multiple(b: &Bencher, benches: &mut [(String, Box<dyn FnMut() -> Du
     let pb_main = mpb.add(ProgressBar::new(benches.len() as u64).with_style(style.clone()));
     pb_main.set_message(b.name.clone());
 
-    for (label, f) in benches.iter_mut() {
+    for (label, f) in benches.iter() {
         let pb = mpb.add(ProgressBar::new(b.nb_measurements as u64).with_style(style.clone()));
         pb.set_message(label.to_string());
 
@@ -131,9 +131,9 @@ pub fn bench_multiple(b: &Bencher, benches: &mut [(String, Box<dyn FnMut() -> Du
 /// same bencher
 /// - f: the piece of code to run and measure
 /// - the measurements will be printed to STDOUT as JSON
-pub fn bench_and_return<F, O>(b: &Bencher, label: &str, mut f: F) -> Option<O>
+pub fn bench_and_return<F, O>(b: &Bencher, label: &str, f: F) -> Option<O>
 where
-    F: FnMut() -> (Duration, O),
+    F: Fn() -> (Duration, O),
 {
     if !b.quiet {
         eprintln!("bencher: {}, label: {}", b.name, label);
@@ -164,9 +164,9 @@ where
 /// # use plnk::timeit;
 /// let t = timeit(|| 1 + 2);
 /// ```
-pub fn timeit<F, O>(mut f: F) -> Duration
+pub fn timeit<F, O>(f: F) -> Duration
 where
-    F: FnMut() -> O,
+    F: Fn() -> O,
 {
     let start_time = Instant::now();
     let _ = f();
@@ -181,9 +181,9 @@ where
 /// let (t, res) = timeit_and_return(|| 1 + 2);
 /// assert_eq!(res, 3);
 /// ```
-pub fn timeit_and_return<F, O>(mut f: F) -> (Duration, O)
+pub fn timeit_and_return<F, O>(f: F) -> (Duration, O)
 where
-    F: FnMut() -> O,
+    F: Fn() -> O,
 {
     let start_time = Instant::now();
     let res = f();