diff --git a/src/func/instances/composition.rs b/src/func/instances/composition.rs
index b7e9155..356fcb5 100644
--- a/src/func/instances/composition.rs
+++ b/src/func/instances/composition.rs
@@ -176,3 +176,41 @@ impl<'a, U: SharedFunctor<'a> + Functor<'a>, V: SharedFunctor<'a>> SharedFunctor
         U::fmap(U::unshare(sa), V::unshare)
     }
 }
+
+#[cfg(test)]
+mod composition_tests {
+    use crate::func::instances::{option::OptionInstance, result::ResultInstance};
+
+    use super::{test_suite, tests, CompositionInstance};
+
+    type T = CompositionInstance<OptionInstance, ResultInstance<i32>>;
+
+    impl<'a> tests::Eqr<'a> for T {
+        fn eqr<A: 'a + Send + PartialEq + std::fmt::Debug>(
+            name: &'a str,
+            left: Self::F<A>,
+            right: Self::F<A>,
+        ) -> tests::R {
+            tests::eqr(name, left, right)
+        }
+    }
+
+    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>>>)>(
+            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))))
+                })
+            });
+        }
+    }
+
+    #[test]
+    fn monad_follows_laws() {
+        test_suite::monad_follows_laws::<T>().unwrap();
+    }
+}
diff --git a/src/func/instances/effect.rs b/src/func/instances/effect.rs
index 0fec3ca..d696efb 100644
--- a/src/func/instances/effect.rs
+++ b/src/func/instances/effect.rs
@@ -232,11 +232,13 @@ mod effect_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|a| WithEffect {
+        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+            mut f: F,
+        ) {
+            f(Box::new(|a| WithEffect {
                 value: a,
                 effect: TestEffect::Sample,
-            });
+            }));
         }
     }
 
diff --git a/src/func/instances/future.rs b/src/func/instances/future.rs
index 5761f68..7de9116 100644
--- a/src/func/instances/future.rs
+++ b/src/func/instances/future.rs
@@ -160,8 +160,10 @@ mod future_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|a| Box::pin(futures::future::ready(a)));
+        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+            mut f: F,
+        ) {
+            f(Box::new(|a| Box::pin(futures::future::ready(a))));
         }
     }
 
diff --git a/src/func/instances/lazy.rs b/src/func/instances/lazy.rs
index ec8adae..2f2c732 100644
--- a/src/func/instances/lazy.rs
+++ b/src/func/instances/lazy.rs
@@ -120,8 +120,10 @@ mod lazy_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|a| Box::new(|| a));
+        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+            mut f: F,
+        ) {
+            f(Box::new(|a| Box::new(|| a)));
         }
     }
 
diff --git a/src/func/instances/option.rs b/src/func/instances/option.rs
index df44f84..613c13c 100644
--- a/src/func/instances/option.rs
+++ b/src/func/instances/option.rs
@@ -149,9 +149,11 @@ mod option_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|_| None);
-            f(&|a| Some(a));
+        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+            mut f: F,
+        ) {
+            f(Box::new(|_| None));
+            f(Box::new(|a| Some(a)));
         }
     }
 
diff --git a/src/func/instances/result.rs b/src/func/instances/result.rs
index 6ba98a7..d7cb140 100644
--- a/src/func/instances/result.rs
+++ b/src/func/instances/result.rs
@@ -263,12 +263,14 @@ mod result_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|_| Err(0));
-            f(&|_| Err(1));
-            f(&|_| Err(2));
-            f(&|_| Err(3));
-            f(&|a| Ok(a));
+        fn sample<A: 'a + Send, F: FnMut(Box<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)));
         }
     }
 
diff --git a/src/func/instances/solo.rs b/src/func/instances/solo.rs
index a06b7e9..5e94996 100644
--- a/src/func/instances/solo.rs
+++ b/src/func/instances/solo.rs
@@ -134,8 +134,10 @@ mod solo_tests {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|a| a);
+        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+            mut f: F,
+        ) {
+            f(Box::new(|a| a));
         }
     }
 
diff --git a/src/func/instances/stackless.rs b/src/func/instances/stackless.rs
index 9b6f3a5..fc47b2f 100644
--- a/src/func/instances/stackless.rs
+++ b/src/func/instances/stackless.rs
@@ -279,8 +279,10 @@ mod stackless_test {
     }
 
     impl<'a> test_suite::FunctorTestSuite<'a> for T {
-        fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(mut f: F) {
-            f(&|a| a.into());
+        fn sample<A: 'a + Send, F: FnMut(Box<dyn test_suite::WrapFunction<'a, A, Self::F<A>>>)>(
+            mut f: F,
+        ) {
+            f(Box::new(|a| a.into()));
         }
     }
 
diff --git a/src/func/test_suite.rs b/src/func/test_suite.rs
index b5357b0..24efcf1 100644
--- a/src/func/test_suite.rs
+++ b/src/func/test_suite.rs
@@ -1,8 +1,20 @@
+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>>;
+}
+
+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())
+    }
+}
+
 pub trait FunctorTestSuite<'a>: WeakFunctor<'a> + Eqr<'a> {
-    fn sample<A: 'a + Send, F: FnMut(&'a (dyn Send + Sync + Fn(A) -> Self::F<A>))>(f: F);
+    fn sample<A: 'a + Send, F: FnMut(Box<dyn WrapFunction<'a, A, Self::F<A>>>)>(f: F);
 }
 
 pub fn functor_follows_laws<'a, T: Functor<'a> + FunctorTestSuite<'a>>() -> R {
@@ -49,7 +61,8 @@ pub fn applicative_follows_laws<'a, T: Applicative<'a> + FunctorTestSuite<'a>>()
     });
     T::sample(|pa| {
         T::sample(|pb| {
-            res += discard_can_be_expressed_via_seq_or_la2::<T, _, _>(|| pa(2), || pb(2));
+            let pa = pa.clone_boxed();
+            res += discard_can_be_expressed_via_seq_or_la2::<T, _, _>(move || pa(2), move || pb(2));
         })
     });
     T::sample(|pa| {
@@ -58,7 +71,7 @@ pub fn applicative_follows_laws<'a, T: Applicative<'a> + FunctorTestSuite<'a>>()
         })
     });
     T::sample(|pa| {
-        res += select_of_equal_is_same::<T, _>(|| pa(2));
+        res += select_of_equal_is_same::<T, _>(move || pa(2));
     });
     res
 }
@@ -66,21 +79,29 @@ pub fn applicative_follows_laws<'a, T: Applicative<'a> + FunctorTestSuite<'a>>()
 pub fn monad_follows_laws<'a, T: Monad<'a> + FunctorTestSuite<'a>>() -> R {
     let mut res = applicative_follows_laws::<T>();
     T::sample(|pa| {
-        res += bind_respects_left_identity::<T, _, _>(|x| pa(x + 3), || 2);
+        res += bind_respects_left_identity::<T, _, _>(move |x| pa(x + 3), || 2);
     });
     T::sample(|pa| {
         res += bind_respects_right_identity::<T, _>(|| pa(2));
     });
     T::sample(|pa| {
         T::sample(|pg| {
+            let pa = pa.clone_boxed();
             T::sample(|pf| {
-                res += bind_is_associative::<T, _, _, _>(|x| pf(x + 5), |x| pg(x + 3), || pa(2));
+                let pg = Arc::new(pg.clone_boxed());
+                let pf = Arc::new(pf);
+                res += bind_is_associative::<T, _, _, _>(
+                    move |x| pf(x + 5),
+                    move |x| pg(x + 3),
+                    || pa(2),
+                );
             })
         })
     });
     T::sample(|pa| {
         T::sample(|pf| {
-            seq_can_be_expressed_via_bind::<T, _, _, _>(|| pf(|x| x + 3), || pa(2));
+            let pa = pa.clone_boxed();
+            seq_can_be_expressed_via_bind::<T, _, _, _>(|| pf(|x| x + 3), move || pa(2));
         })
     });
     T::sample(|pa| {
@@ -93,7 +114,14 @@ pub fn monad_follows_laws<'a, T: Monad<'a> + FunctorTestSuite<'a>>() -> R {
     });
     T::sample(|pa| {
         T::sample(|pb| {
-            res += iterate_can_be_expressed_via_bind::<T, _, _, _>(|| pa(2), || |x| pb(x + 3));
+            let pa = pa.clone_boxed();
+            res += iterate_can_be_expressed_via_bind::<T, _, _, _>(
+                move || pa(2),
+                move || {
+                    let pb = pb.clone_boxed();
+                    move |x| pb(x + 3)
+                },
+            );
         })
     });
     res