diff --git a/src/abstract_tree/assignment.rs b/src/abstract_tree/assignment.rs
index c4fcdf4..71f3720 100644
--- a/src/abstract_tree/assignment.rs
+++ b/src/abstract_tree/assignment.rs
@@ -4,12 +4,12 @@ use super::{AbstractTree, Identifier, Statement};
 
 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub struct Assignment<'src> {
-    identifier: Identifier<'src>,
+    identifier: Identifier,
     statement: Box<Statement<'src>>,
 }
 
 impl<'src> Assignment<'src> {
-    pub fn new(identifier: Identifier<'src>, statement: Statement<'src>) -> Self {
+    pub fn new(identifier: Identifier, statement: Statement<'src>) -> Self {
         Self {
             identifier,
             statement: Box::new(statement),
diff --git a/src/abstract_tree/expression.rs b/src/abstract_tree/expression.rs
index d19e81a..01adb2a 100644
--- a/src/abstract_tree/expression.rs
+++ b/src/abstract_tree/expression.rs
@@ -4,7 +4,7 @@ use super::{AbstractTree, Identifier, Logic, ValueNode};
 
 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
 pub enum Expression<'src> {
-    Identifier(Identifier<'src>),
+    Identifier(Identifier),
     Logic(Box<Logic<'src>>),
     Value(ValueNode<'src>),
 }
diff --git a/src/abstract_tree/identifier.rs b/src/abstract_tree/identifier.rs
index 3f545c7..2bdaf32 100644
--- a/src/abstract_tree/identifier.rs
+++ b/src/abstract_tree/identifier.rs
@@ -1,17 +1,19 @@
+use std::sync::Arc;
+
 use crate::{context::Context, error::RuntimeError, Value};
 
 use super::AbstractTree;
 
 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
-pub struct Identifier<'src>(&'src str);
+pub struct Identifier(Arc<String>);
 
-impl<'src> Identifier<'src> {
-    pub fn new(string: &'src str) -> Self {
-        Identifier(string)
+impl Identifier {
+    pub fn new<T: ToString>(string: T) -> Self {
+        Identifier(Arc::new(string.to_string()))
     }
 }
 
-impl<'src> AbstractTree for Identifier<'src> {
+impl AbstractTree for Identifier {
     fn run(self, _context: &Context) -> Result<Value, RuntimeError> {
         todo!()
         // let value = context.get(&self)?.unwrap_or_else(Value::none).clone();
diff --git a/src/abstract_tree/value_node.rs b/src/abstract_tree/value_node.rs
index 898663c..030f96f 100644
--- a/src/abstract_tree/value_node.rs
+++ b/src/abstract_tree/value_node.rs
@@ -10,10 +10,27 @@ pub enum ValueNode<'src> {
     Float(f64),
     Integer(i64),
     List(Vec<Expression<'src>>),
-    Map(BTreeMap<Identifier<'src>, Expression<'src>>),
+    Map(BTreeMap<Identifier, Expression<'src>>),
     Range(Range<i64>),
     String(&'src str),
-    Enum(&'src str, &'src str),
+    Enum(Identifier, Identifier),
+}
+
+impl<'src> AbstractTree for ValueNode<'src> {
+    fn run(self, _context: &Context) -> Result<Value, RuntimeError> {
+        let value = match self {
+            ValueNode::Boolean(boolean) => Value::boolean(boolean),
+            ValueNode::Float(float) => todo!(),
+            ValueNode::Integer(integer) => todo!(),
+            ValueNode::List(expression_list) => todo!(),
+            ValueNode::Map(property_list) => todo!(),
+            ValueNode::Range(range) => todo!(),
+            ValueNode::String(string) => todo!(),
+            ValueNode::Enum(name, variant) => todo!(),
+        };
+
+        Ok(value)
+    }
 }
 
 impl<'src> Eq for ValueNode<'src> {}
@@ -64,9 +81,3 @@ impl<'src> Ord for ValueNode<'src> {
         }
     }
 }
-
-impl<'src> AbstractTree for ValueNode<'src> {
-    fn run(self, _context: &Context) -> Result<Value, RuntimeError> {
-        todo!()
-    }
-}
diff --git a/src/context.rs b/src/context.rs
index 9859894..d3f7349 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -3,10 +3,10 @@ use std::{
     sync::{Arc, RwLock},
 };
 
-use crate::{error::RwLockPoisonError, Value};
+use crate::{abstract_tree::Identifier, error::RwLockPoisonError, Value};
 
 pub struct Context {
-    inner: Arc<RwLock<BTreeMap<String, Value>>>,
+    inner: Arc<RwLock<BTreeMap<Identifier, Value>>>,
 }
 
 impl Context {
@@ -16,20 +16,20 @@ impl Context {
         }
     }
 
-    pub fn with_values(values: BTreeMap<String, Value>) -> Self {
+    pub fn with_values(values: BTreeMap<Identifier, Value>) -> Self {
         Self {
             inner: Arc::new(RwLock::new(values)),
         }
     }
 
-    pub fn get(&self, key: &str) -> Result<Option<Value>, RwLockPoisonError> {
-        let value = self.inner.read()?.get(key).cloned();
+    pub fn get(&self, identifier: &Identifier) -> Result<Option<Value>, RwLockPoisonError> {
+        let value = self.inner.read()?.get(identifier).cloned();
 
         Ok(value)
     }
 
-    pub fn set(&self, key: String, value: Value) -> Result<(), RwLockPoisonError> {
-        self.inner.write()?.insert(key, value);
+    pub fn set(&self, identifier: Identifier, value: Value) -> Result<(), RwLockPoisonError> {
+        self.inner.write()?.insert(identifier, value);
 
         Ok(())
     }
diff --git a/src/lexer.rs b/src/lexer.rs
index fc1814c..361fd16 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -4,14 +4,13 @@ use crate::error::Error;
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum Token<'src> {
-    None,
     Boolean(bool),
     Integer(i64),
     Float(f64),
     String(&'src str),
     Identifier(&'src str),
     Operator(&'src str),
-    Control(char),
+    Control(&'src str),
 }
 
 pub fn lex<'src>(source: &'src str) -> Result<Vec<(Token, SimpleSpan)>, Error<'src>> {
@@ -84,7 +83,18 @@ pub fn lexer<'src>() -> impl Parser<
     ))
     .map(Token::Operator);
 
-    let control = one_of("[](){},;'").map(Token::Control);
+    let control = choice((
+        just("[").padded(),
+        just("]").padded(),
+        just("(").padded(),
+        just(")").padded(),
+        just("{").padded(),
+        just("}").padded(),
+        just(",").padded(),
+        just(";").padded(),
+        just("::").padded(),
+    ))
+    .map(Token::Control);
 
     choice((
         boolean, float, integer, string, identifier, operator, control,
diff --git a/src/parser.rs b/src/parser.rs
index 57db169..4101d4f 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,3 +1,5 @@
+use std::{cell::RefCell, collections::HashMap};
+
 use chumsky::{input::SpannedInput, pratt::*, prelude::*};
 
 use crate::{abstract_tree::*, error::Error, lexer::Token};
@@ -11,43 +13,63 @@ fn parser<'tokens, 'src: 'tokens>() -> impl Parser<
     Vec<(Statement<'src>, SimpleSpan)>,
     extra::Err<Rich<'tokens, Token<'src>, SimpleSpan>>,
 > {
+    let identifiers: RefCell<HashMap<&str, Identifier>> = RefCell::new(HashMap::new());
+
     let identifier = select! {
-        Token::Identifier(text) => Identifier::new(text),
+        Token::Identifier(text) => {
+            let mut identifiers = identifiers.borrow_mut();
+
+            if let Some(identifier) = identifiers.get(&text) {
+                identifier.clone()
+            } else {
+                let new = Identifier::new(text);
+
+                identifiers.insert(text, new.clone());
+
+                new
+            }
+        }
     };
 
     let expression = recursive(|expression| {
         let basic_value = select! {
-            Token::None => ValueNode::Enum("Option", "None"),
             Token::Boolean(boolean) => ValueNode::Boolean(boolean),
             Token::Integer(integer) => ValueNode::Integer(integer),
             Token::Float(float) => ValueNode::Float(float),
             Token::String(string) => ValueNode::String(string),
-        };
+        }
+        .map(|value| Expression::Value(value))
+        .boxed();
 
         let identifier_expression = identifier
+            .clone()
             .map(|identifier| Expression::Identifier(identifier))
             .boxed();
 
         let list = expression
             .clone()
-            .separated_by(just(Token::Control(',')))
+            .separated_by(just(Token::Control(",")))
             .allow_trailing()
             .collect()
-            .delimited_by(just(Token::Control('[')), just(Token::Control(']')))
-            .map(ValueNode::List);
+            .delimited_by(just(Token::Control("[")), just(Token::Control("]")))
+            .map(|list| Expression::Value(ValueNode::List(list)))
+            .boxed();
 
-        let value = choice((
-            basic_value.map(|value| Expression::Value(value)),
-            list.map(|list| Expression::Value(list)),
-        ))
-        .boxed();
+        let r#enum = identifier
+            .clone()
+            .then_ignore(just(Token::Control("::")))
+            .then(identifier.clone())
+            .map(|(name, variant)| Expression::Value(ValueNode::Enum(name, variant)))
+            .boxed();
 
         let atom = choice((
             identifier_expression.clone(),
-            value.clone(),
+            basic_value.clone(),
+            list.clone(),
+            r#enum.clone(),
             expression
                 .clone()
-                .delimited_by(just(Token::Control('(')), just(Token::Control(')'))),
+                .delimited_by(just(Token::Control("(")), just(Token::Control(")"))),
         ));
 
         let logic = atom
@@ -82,7 +104,7 @@ fn parser<'tokens, 'src: 'tokens>() -> impl Parser<
             ))
             .boxed();
 
-        choice([logic, identifier_expression, value])
+        choice([r#enum, logic, identifier_expression, list, basic_value])
     });
 
     let statement = recursive(|statement| {
@@ -191,6 +213,17 @@ mod tests {
         );
     }
 
+    #[test]
+    fn r#enum() {
+        assert_eq!(
+            parse(&lex("Option::None").unwrap()).unwrap()[0].0,
+            Statement::Expression(Expression::Value(ValueNode::Enum(
+                Identifier::new("Option"),
+                Identifier::new("None")
+            )))
+        );
+    }
+
     #[test]
     fn list() {
         assert_eq!(