diff --git a/src/func/classes/option.rs b/src/func/classes/option.rs
index 19804a0..b37775c 100644
--- a/src/func/classes/option.rs
+++ b/src/func/classes/option.rs
@@ -21,8 +21,19 @@ impl Functor for OptionClass {
         fa.map(f)
     }
 
-    fn replace<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, b: B) -> Self::F<'a, B> {
-        fa.map(|_| b)
+    fn replace<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, b: B) -> Self::F<'a, B>
+    where
+        Self: 'a,
+    {
+        fa?;
+        Self::pure(b)
+    }
+
+    fn void<'a, A: 'a>(fa: Self::F<'a, A>) -> Self::F<'a, ()>
+        where
+            Self: 'a, {
+        fa?;
+        Self::pure(())
     }
 }
 
diff --git a/src/func/classes/result.rs b/src/func/classes/result.rs
index ef3caa1..5509e10 100644
--- a/src/func/classes/result.rs
+++ b/src/func/classes/result.rs
@@ -28,7 +28,15 @@ impl<E> Functor for ResultClass<E> {
     where
         Self: 'a,
     {
-        fa.map(|_| b)
+        fa?;
+        Self::pure(b)
+    }
+
+    fn void<'a, A: 'a>(fa: Self::F<'a, A>) -> Self::F<'a, ()>
+        where
+            Self: 'a, {
+        fa?;
+        Self::pure(())
     }
 }