diff --git a/types/src/object.rs b/types/src/object.rs
index d25df2e..3c9baf3 100644
--- a/types/src/object.rs
+++ b/types/src/object.rs
@@ -28,9 +28,12 @@ pub trait Object:
     fmt::Debug +
     fmt::Display
 {
+    /// Cast this Object to an Any.
     fn as_any(&self) -> &Any;
-    fn as_pair(&self) -> Option<&Pair>;
-    fn as_sym(&self) -> Option<&Sym>;
+    /// Cast this Object to a Pair if possible.
+    fn as_pair(&self) -> Option<&Pair> { None }
+    /// Cast this Object to a Sym if possible.
+    fn as_sym(&self) -> Option<&Sym> { None }
 }
 
 impl Obj {
diff --git a/types/src/pair.rs b/types/src/pair.rs
index ecb4c46..b142c25 100644
--- a/types/src/pair.rs
+++ b/types/src/pair.rs
@@ -43,7 +43,6 @@ impl Pair {
 impl Object for Pair {
     fn as_any(&self) -> &Any { self }
     fn as_pair(&self) -> Option<&Pair> { Some(self) }
-    fn as_sym(&self) -> Option<&Sym> { None }
 }
 
 impl fmt::Display for Pair {
diff --git a/types/src/sym.rs b/types/src/sym.rs
index a502d5c..3c47599 100644
--- a/types/src/sym.rs
+++ b/types/src/sym.rs
@@ -24,7 +24,6 @@ impl Sym {
 
 impl Object for Sym {
     fn as_any(&self) -> &Any { self }
-    fn as_pair(&self) -> Option<&Pair> { None }
     fn as_sym(&self) -> Option<&Sym> { Some(self) }
 }