diff --git a/src/func/instances/composition.rs b/src/func/instances/composition.rs
index 356fcb5..37b7cc5 100644
--- a/src/func/instances/composition.rs
+++ b/src/func/instances/composition.rs
@@ -179,6 +179,8 @@ impl<'a, U: SharedFunctor<'a> + Functor<'a>, V: SharedFunctor<'a>> SharedFunctor
 
 #[cfg(test)]
 mod composition_tests {
+    use std::sync::Arc;
+
     use crate::func::instances::{option::OptionInstance, result::ResultInstance};
 
     use super::{test_suite, tests, CompositionInstance};
@@ -196,14 +198,13 @@ mod composition_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
             OptionInstance::sample(|ua0| {
                 ResultInstance::sample(|a0| {
-                    let ua0 = std::sync::Arc::new(ua0.clone_boxed());
-                    let a0 = std::sync::Arc::new(a0.clone_boxed());
-                    f(Box::new(move |a| ua0(a0(a))))
+                    let ua0 = ua0.clone();
+                    f(Arc::new(move |a| ua0(a0(a))))
                 })
             });
         }
diff --git a/src/func/instances/effect.rs b/src/func/instances/effect.rs
index d696efb..9fef2ea 100644
--- a/src/func/instances/effect.rs
+++ b/src/func/instances/effect.rs
@@ -162,6 +162,8 @@ impl<'a, E: 'a + Send> LocalFunctor<'a> for EffectInstance<E> {
 
 #[cfg(test)]
 mod effect_tests {
+    use std::sync::Arc;
+
     use super::{test_suite, tests, Effect, EffectInstance, WithEffect};
 
     #[derive(Debug, PartialEq)]
@@ -232,10 +234,10 @@ mod effect_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|a| WithEffect {
+            f(Arc::new(|a| WithEffect {
                 value: a,
                 effect: TestEffect::Sample,
             }));
diff --git a/src/func/instances/future.rs b/src/func/instances/future.rs
index 7de9116..8c2208b 100644
--- a/src/func/instances/future.rs
+++ b/src/func/instances/future.rs
@@ -139,6 +139,8 @@ impl<'a> SharedFunctor<'a> for FutureInstance {
 
 #[cfg(test)]
 mod future_tests {
+    use std::sync::Arc;
+
     use crate::func::{applicative_select::Selected, tests::Eqr, ApplicativeSelect};
 
     use super::{test_suite, tests, FutureInstance};
@@ -160,10 +162,10 @@ mod future_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|a| Box::pin(futures::future::ready(a))));
+            f(Arc::new(|a| Box::pin(futures::future::ready(a))));
         }
     }
 
diff --git a/src/func/instances/lazy.rs b/src/func/instances/lazy.rs
index 2f2c732..0774c97 100644
--- a/src/func/instances/lazy.rs
+++ b/src/func/instances/lazy.rs
@@ -105,6 +105,8 @@ impl<'a> Monad<'a> for LazyInstance {
 
 #[cfg(test)]
 mod lazy_tests {
+    use std::sync::Arc;
+
     use super::{test_suite, tests, LazyInstance};
 
     type T = LazyInstance;
@@ -120,10 +122,10 @@ mod lazy_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|a| Box::new(|| a)));
+            f(Arc::new(|a| Box::new(|| a)));
         }
     }
 
diff --git a/src/func/instances/option.rs b/src/func/instances/option.rs
index 613c13c..b6e0578 100644
--- a/src/func/instances/option.rs
+++ b/src/func/instances/option.rs
@@ -134,6 +134,8 @@ impl<'a> Fail<'a, ()> for OptionInstance {
 
 #[cfg(test)]
 mod option_tests {
+    use std::sync::Arc;
+
     use super::{test_suite, tests, Functor};
 
     use super::OptionInstance as T;
@@ -149,11 +151,11 @@ mod option_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|_| None));
-            f(Box::new(|a| Some(a)));
+            f(Arc::new(|_| None));
+            f(Arc::new(|a| Some(a)));
         }
     }
 
diff --git a/src/func/instances/result.rs b/src/func/instances/result.rs
index d7cb140..7f25683 100644
--- a/src/func/instances/result.rs
+++ b/src/func/instances/result.rs
@@ -248,6 +248,8 @@ impl<'a, T: Monad<'a>> MonadFailAny<'a> for ResultFailOver<T> {
 
 #[cfg(test)]
 mod result_tests {
+    use std::sync::Arc;
+
     use super::{test_suite, tests, ResultInstance};
 
     type T = ResultInstance<i32>;
@@ -263,14 +265,14 @@ mod result_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|_| Err(0)));
-            f(Box::new(|_| Err(1)));
-            f(Box::new(|_| Err(2)));
-            f(Box::new(|_| Err(3)));
-            f(Box::new(|a| Ok(a)));
+            f(Arc::new(|_| Err(0)));
+            f(Arc::new(|_| Err(1)));
+            f(Arc::new(|_| Err(2)));
+            f(Arc::new(|_| Err(3)));
+            f(Arc::new(|a| Ok(a)));
         }
     }
 
diff --git a/src/func/instances/solo.rs b/src/func/instances/solo.rs
index 5e94996..ac5f5a1 100644
--- a/src/func/instances/solo.rs
+++ b/src/func/instances/solo.rs
@@ -119,6 +119,8 @@ impl<'a> Fail<'a, std::convert::Infallible> for SoloInstance {
 
 #[cfg(test)]
 mod solo_tests {
+    use std::sync::Arc;
+
     use super::{test_suite, tests, SoloInstance};
 
     type T = SoloInstance;
@@ -134,10 +136,10 @@ mod solo_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|a| a));
+            f(Arc::new(|a| a));
         }
     }
 
diff --git a/src/func/instances/stackless.rs b/src/func/instances/stackless.rs
index fc47b2f..8890949 100644
--- a/src/func/instances/stackless.rs
+++ b/src/func/instances/stackless.rs
@@ -262,6 +262,8 @@ impl<'a> Monad<'a> for StacklessInstance {
 
 #[cfg(test)]
 mod stackless_test {
+    use std::sync::Arc;
+
     use crate::func::*;
 
     use super::{test_suite, tests, Stackless};
@@ -279,10 +281,10 @@ mod stackless_test {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+        fn sample<A: 'a + Send, F: FnMut(Arc<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
             mut f: F,
         ) {
-            f(Box::new(|a| a.into()));
+            f(Arc::new(|a| a.into()));
         }
     }
 
diff --git a/src/func/test_suite.rs b/src/func/test_suite.rs
index 24efcf1..fba8de6 100644
--- a/src/func/test_suite.rs
+++ b/src/func/test_suite.rs
@@ -3,18 +3,12 @@ use std::sync::Arc;
 use super::tests::*;
 use super::*;
 
-pub trait WrapFunction<'a, A, B>: 'a + Send + Sync + Fn(A) -> B {
-    fn clone_boxed(&self) -> Box<dyn WrapFunction<'a, A, B>>;
-}
+pub trait WrapFunction<'a, A, B>: 'a + Send + Sync + Fn(A) -> B {}
 
-impl<'a, A, B, F: 'a + Send + Sync + Clone + Fn(A) -> B> WrapFunction<'a, A, B> for F {
-    fn clone_boxed(&self) -> Box<dyn WrapFunction<'a, A, B>> {
-        Box::new(self.clone())
-    }
-}
+impl<'a, A, B, F: 'a + Send + Sync + Clone + Fn(A) -> B> WrapFunction<'a, A, B> for F {}
 
 pub trait FunctorTestSuite<'a>: WeakFunctor<'a> + Eqr<'a> {
-    fn sample<A: 'a + Send, F: FnMut(Box<dyn WrapFunction<'a, A, Self::F<A>>>)>(f: F);
+    fn sample<A: 'a + Send, F: FnMut(Arc<dyn WrapFunction<'a, A, Self::F<A>>>)>(f: F);
 }
 
 pub fn functor_follows_laws<'a, T: Functor<'a> + FunctorTestSuite<'a>>() -> R {
@@ -61,7 +55,7 @@ pub fn applicative_follows_laws<'a, T: Applicative<'a> + FunctorTestSuite<'a>>()
     });
     T::sample(|pa| {
         T::sample(|pb| {
-            let pa = pa.clone_boxed();
+            let pa = pa.clone();
             res += discard_can_be_expressed_via_seq_or_la2::<T, _, _>(move || pa(2), move || pb(2));
         })
     });
@@ -86,10 +80,9 @@ pub fn monad_follows_laws<'a, T: Monad<'a> + FunctorTestSuite<'a>>() -> R {
     });
     T::sample(|pa| {
         T::sample(|pg| {
-            let pa = pa.clone_boxed();
+            let pa = pa.clone();
             T::sample(|pf| {
-                let pg = Arc::new(pg.clone_boxed());
-                let pf = Arc::new(pf);
+                let pg = pg.clone();
                 res += bind_is_associative::<T, _, _, _>(
                     move |x| pf(x + 5),
                     move |x| pg(x + 3),
@@ -100,7 +93,7 @@ pub fn monad_follows_laws<'a, T: Monad<'a> + FunctorTestSuite<'a>>() -> R {
     });
     T::sample(|pa| {
         T::sample(|pf| {
-            let pa = pa.clone_boxed();
+            let pa = pa.clone();
             seq_can_be_expressed_via_bind::<T, _, _, _>(|| pf(|x| x + 3), move || pa(2));
         })
     });
@@ -114,11 +107,11 @@ pub fn monad_follows_laws<'a, T: Monad<'a> + FunctorTestSuite<'a>>() -> R {
     });
     T::sample(|pa| {
         T::sample(|pb| {
-            let pa = pa.clone_boxed();
+            let pa = pa.clone();
             res += iterate_can_be_expressed_via_bind::<T, _, _, _>(
                 move || pa(2),
                 move || {
-                    let pb = pb.clone_boxed();
+                    let pb = pb.clone();
                     move |x| pb(x + 3)
                 },
             );