diff --git a/src/built_in_identifiers.rs b/src/built_in_identifiers.rs
index c6f5061..8659ad5 100644
--- a/src/built_in_identifiers.rs
+++ b/src/built_in_identifiers.rs
@@ -10,22 +10,42 @@ pub fn all_built_in_identifiers() -> impl Iterator<Item = BuiltInIdentifier> {
 
 static OPTION: OnceLock<Identifier> = OnceLock::new();
 static NONE: OnceLock<Identifier> = OnceLock::new();
+static SOME: OnceLock<Identifier> = OnceLock::new();
+static RESULT: OnceLock<Identifier> = OnceLock::new();
+static OK: OnceLock<Identifier> = OnceLock::new();
+static ERROR: OnceLock<Identifier> = OnceLock::new();
 
 #[derive(Sequence, Debug)]
 pub enum BuiltInIdentifier {
     Option,
     None,
+    Some,
+    Result,
+    Ok,
+    Error,
 }
 
 impl BuiltInIdentifier {
-    pub fn get(&self) -> Identifier {
+    pub fn get(&self) -> &Identifier {
         match self {
-            BuiltInIdentifier::Option => OPTION
-                .get_or_init(|| Identifier::from_raw_parts(Arc::new("Option".to_string())))
-                .clone(),
-            BuiltInIdentifier::None => NONE
-                .get_or_init(|| Identifier::from_raw_parts(Arc::new("None".to_string())))
-                .clone(),
+            BuiltInIdentifier::Option => {
+                OPTION.get_or_init(|| Identifier::from_raw_parts(Arc::new("Option".to_string())))
+            }
+            BuiltInIdentifier::None => {
+                NONE.get_or_init(|| Identifier::from_raw_parts(Arc::new("None".to_string())))
+            }
+            BuiltInIdentifier::Some => {
+                SOME.get_or_init(|| Identifier::from_raw_parts(Arc::new("Some".to_string())))
+            }
+            BuiltInIdentifier::Result => {
+                RESULT.get_or_init(|| Identifier::from_raw_parts(Arc::new("Result".to_string())))
+            }
+            BuiltInIdentifier::Ok => {
+                OK.get_or_init(|| Identifier::from_raw_parts(Arc::new("Ok".to_string())))
+            }
+            BuiltInIdentifier::Error => {
+                ERROR.get_or_init(|| Identifier::from_raw_parts(Arc::new("Error".to_string())))
+            }
         }
     }
 }
diff --git a/src/value/mod.rs b/src/value/mod.rs
index 2b256dd..7249521 100644
--- a/src/value/mod.rs
+++ b/src/value/mod.rs
@@ -35,16 +35,16 @@ pub mod struct_instance;
 /// value that can be treated as any other.
 #[derive(Debug, Clone)]
 pub enum Value {
+    Boolean(bool),
+    Enum(EnumInstance),
+    Float(f64),
+    Function(Function),
+    Integer(i64),
     List(List),
     Map(Map),
-    Function(Function),
-    String(String),
-    Float(f64),
-    Integer(i64),
-    Boolean(bool),
     Range(RangeInclusive<i64>),
+    String(String),
     Struct(StructInstance),
-    Enum(EnumInstance),
 }
 
 impl Value {