diff --git a/src/abstract_tree/built_in_value.rs b/src/abstract_tree/built_in_value.rs
index 8ee01e8..6f9232e 100644
--- a/src/abstract_tree/built_in_value.rs
+++ b/src/abstract_tree/built_in_value.rs
@@ -31,12 +31,12 @@ impl BuiltInValue {
         match self {
             BuiltInValue::Args => Type::list(Type::String),
             BuiltInValue::AssertEqual => BuiltInFunction::AssertEqual.r#type(),
-            BuiltInValue::Fs => Type::Map,
-            BuiltInValue::Json => Type::Map,
+            BuiltInValue::Fs => Type::Map(None),
+            BuiltInValue::Json => Type::Map(None),
             BuiltInValue::Length => BuiltInFunction::Length.r#type(),
             BuiltInValue::Output => BuiltInFunction::Output.r#type(),
-            BuiltInValue::Random => Type::Map,
-            BuiltInValue::String => Type::Map,
+            BuiltInValue::Random => Type::Map(None),
+            BuiltInValue::String => Type::Map(None),
         }
     }
 
diff --git a/src/abstract_tree/index.rs b/src/abstract_tree/index.rs
index 2c19511..32def88 100644
--- a/src/abstract_tree/index.rs
+++ b/src/abstract_tree/index.rs
@@ -92,7 +92,7 @@ impl AbstractTree for Index {
     fn expected_type(&self, context: &Map) -> Result<Type> {
         match self.collection.expected_type(context)? {
             Type::List(item_type) => Ok(*item_type.clone()),
-            Type::Map => Ok(Type::Any),
+            Type::Map(_) => Ok(Type::Any),
             Type::None => Ok(Type::None),
             r#type => Ok(r#type),
         }
diff --git a/src/abstract_tree/mod.rs b/src/abstract_tree/mod.rs
index dd64b8c..caf662a 100644
--- a/src/abstract_tree/mod.rs
+++ b/src/abstract_tree/mod.rs
@@ -40,7 +40,7 @@ use tree_sitter::Node;
 
 use crate::{Error, Map, Result, Value};
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct SyntaxPosition {
     pub start_byte: usize,
     pub end_byte: usize,
@@ -63,6 +63,7 @@ impl From<tree_sitter::Range> for SyntaxPosition {
     }
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct Root {
     statements: Vec<Statement>,
 }
diff --git a/src/abstract_tree/type_definition.rs b/src/abstract_tree/type_definition.rs
index 083db30..511ed32 100644
--- a/src/abstract_tree/type_definition.rs
+++ b/src/abstract_tree/type_definition.rs
@@ -3,7 +3,7 @@ use std::fmt::{self, Display, Formatter};
 use serde::{Deserialize, Serialize};
 use tree_sitter::Node;
 
-use crate::{AbstractTree, Error, Map, Result, Value};
+use crate::{AbstractTree, Error, Map, Result, Structure, Value};
 
 #[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
 pub struct TypeDefinition {
@@ -61,7 +61,7 @@ pub enum Type {
     },
     Integer,
     List(Box<Type>),
-    Map,
+    Map(Option<Structure>),
     None,
     Number,
     String,
@@ -92,13 +92,13 @@ impl Type {
             | (Type::Collection, Type::Collection)
             | (Type::Collection, Type::List(_))
             | (Type::List(_), Type::Collection)
-            | (Type::Collection, Type::Map)
-            | (Type::Map, Type::Collection)
+            | (Type::Collection, Type::Map(_))
+            | (Type::Map(_), Type::Collection)
             | (Type::Collection, Type::String)
             | (Type::String, Type::Collection)
             | (Type::Float, Type::Float)
             | (Type::Integer, Type::Integer)
-            | (Type::Map, Type::Map)
+            | (Type::Map(_), Type::Map(_))
             | (Type::Number, Type::Number)
             | (Type::Number, Type::Integer)
             | (Type::Number, Type::Float)
@@ -215,7 +215,7 @@ impl AbstractTree for Type {
                 }
             }
             "int" => Type::Integer,
-            "map" => Type::Map,
+            "map" => Type::Map(None),
             "num" => Type::Number,
             "none" => Type::None,
             "str" => Type::String,
@@ -273,7 +273,7 @@ impl Display for Type {
             }
             Type::Integer => write!(f, "int"),
             Type::List(item_type) => write!(f, "[{item_type}]"),
-            Type::Map => write!(f, "map"),
+            Type::Map(_) => write!(f, "map"),
             Type::Number => write!(f, "num"),
             Type::None => write!(f, "none"),
             Type::String => write!(f, "str"),
diff --git a/src/abstract_tree/value_node.rs b/src/abstract_tree/value_node.rs
index d7ed53f..4766c88 100644
--- a/src/abstract_tree/value_node.rs
+++ b/src/abstract_tree/value_node.rs
@@ -5,7 +5,7 @@ use tree_sitter::Node;
 
 use crate::{
     AbstractTree, BuiltInValue, Error, Expression, Function, Identifier, List, Map, Result,
-    Statement, Type, TypeDefinition, Value,
+    Statement, Structure, Type, TypeDefinition, Value,
 };
 
 #[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
@@ -116,7 +116,7 @@ impl AbstractTree for ValueNode {
                 let mut current_type: Option<Type> = None;
                 let mut current_statement = None;
 
-                for index in 0..child.child_count() - 1 {
+                for index in 2..child.child_count() - 1 {
                     let child_syntax_node = child.child(index).unwrap();
 
                     if child_syntax_node.kind() == "identifier" {
@@ -151,9 +151,15 @@ impl AbstractTree for ValueNode {
                             context,
                         )?);
 
-                        if let (Some(identifier), Some(r#type)) =
-                            (&current_identifier, &current_type)
-                        {
+                        if let Some(identifier) = &current_identifier {
+                            let r#type = if let Some(r#type) = &current_type {
+                                r#type.clone()
+                            } else if let Some(statement) = &current_statement {
+                                statement.expected_type(context)?
+                            } else {
+                                Type::None
+                            };
+
                             btree_map.insert(
                                 identifier.inner().clone(),
                                 (current_statement.clone(), r#type.clone()),
@@ -223,16 +229,16 @@ impl AbstractTree for ValueNode {
                 let mut value_map = BTreeMap::new();
 
                 for (key, (statement_option, r#type)) in node_map {
-                    let value = if let Some(statement) = statement_option {
-                        statement.run(source, context)?
+                    let value_option = if let Some(statement) = statement_option {
+                        Some(statement.run(source, context)?)
                     } else {
-                        Value::none()
+                        None
                     };
 
-                    value_map.insert(key.to_string(), (Some(value), r#type.clone()));
+                    value_map.insert(key.to_string(), (value_option, r#type.clone()));
                 }
 
-                Value::Structure(value_map)
+                Value::Structure(Structure::new(value_map))
             }
         };
 
@@ -274,9 +280,17 @@ impl AbstractTree for ValueNode {
                     Type::None
                 }
             }
-            ValueNode::Map(_) => Type::Map,
+            ValueNode::Map(_) => Type::Map(None),
             ValueNode::BuiltInValue(built_in_value) => built_in_value.expected_type(context)?,
-            ValueNode::Structure(_) => todo!(),
+            ValueNode::Structure(node_map) => {
+                let mut value_map = BTreeMap::new();
+
+                for (key, (_statement_option, r#type)) in node_map {
+                    value_map.insert(key.to_string(), (None, r#type.clone()));
+                }
+
+                Type::Map(Some(Structure::new(value_map)))
+            }
         };
 
         Ok(r#type)
diff --git a/src/lib.rs b/src/lib.rs
index 92b79fb..e4b3924 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,7 +8,7 @@ pub use crate::{
     built_in_functions::BuiltInFunction,
     error::*,
     interpret::*,
-    value::{function::Function, list::List, map::Map, Value},
+    value::{function::Function, list::List, map::Map, structure::Structure, Value},
 };
 
 pub use tree_sitter::Node as SyntaxNode;
diff --git a/src/value/map.rs b/src/value/map.rs
index 11f69d9..0102fc4 100644
--- a/src/value/map.rs
+++ b/src/value/map.rs
@@ -11,7 +11,7 @@ use std::{
     sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard},
 };
 
-use crate::{value::Value, Result, Type};
+use crate::{value::Value, Result, Structure, Type};
 
 /// A collection dust variables comprised of key-value pairs.
 ///
@@ -20,6 +20,7 @@ use crate::{value::Value, Result, Type};
 #[derive(Clone, Debug)]
 pub struct Map {
     variables: Arc<RwLock<BTreeMap<String, (Value, Type)>>>,
+    structure: Option<Structure>,
 }
 
 impl Map {
@@ -27,6 +28,7 @@ impl Map {
     pub fn new() -> Self {
         Map {
             variables: Arc::new(RwLock::new(BTreeMap::new())),
+            structure: None,
         }
     }
 
@@ -39,6 +41,7 @@ impl Map {
 
         Ok(Map {
             variables: Arc::new(RwLock::new(new_map)),
+            structure: other.structure.clone(),
         })
     }
 
diff --git a/src/value/mod.rs b/src/value/mod.rs
index 3098689..5db9c85 100644
--- a/src/value/mod.rs
+++ b/src/value/mod.rs
@@ -1,7 +1,7 @@
 //! Types that represent runtime values.
 use crate::{
     error::{Error, Result},
-    Function, Identifier, List, Map, Type, TypeDefinition,
+    Function, Identifier, List, Map, Structure, Type, TypeDefinition,
 };
 
 use serde::{
@@ -12,7 +12,6 @@ use serde::{
 
 use std::{
     cmp::Ordering,
-    collections::BTreeMap,
     convert::TryFrom,
     fmt::{self, Display, Formatter},
     marker::PhantomData,
@@ -23,6 +22,7 @@ use std::{
 pub mod function;
 pub mod list;
 pub mod map;
+pub mod structure;
 
 /// Dust value representation.
 ///
@@ -39,7 +39,7 @@ pub enum Value {
     Integer(i64),
     Boolean(bool),
     Option(Option<Box<Value>>),
-    Structure(BTreeMap<String, (Option<Value>, Type)>),
+    Structure(Structure),
 }
 
 impl Default for Value {
@@ -86,7 +86,7 @@ impl Value {
                     ));
                 }
 
-                Type::Map
+                Type::Map(None)
             }
             Value::Function(function) => function.r#type().clone(),
             Value::String(_) => Type::String,
@@ -541,18 +541,7 @@ impl Display for Value {
             Value::List(list) => write!(f, "{list}"),
             Value::Map(map) => write!(f, "{map}"),
             Value::Function(function) => write!(f, "{function}"),
-            Value::Structure(btree_map) => {
-                writeln!(f, "{{")?;
-
-                for (key, (value_option, r#type)) in btree_map {
-                    if let Some(value) = value_option {
-                        writeln!(f, "  {key} {} = {value}", r#type)?;
-                    } else {
-                        writeln!(f, "  {key} {}", r#type)?;
-                    }
-                }
-                write!(f, "}}")
-            }
+            Value::Structure(structure) => write!(f, "{structure}"),
         }
     }
 }
diff --git a/src/value/structure.rs b/src/value/structure.rs
new file mode 100644
index 0000000..f780dbf
--- /dev/null
+++ b/src/value/structure.rs
@@ -0,0 +1,37 @@
+use std::{
+    collections::BTreeMap,
+    fmt::{self, Display, Formatter},
+    sync::Arc,
+};
+
+use serde::{Deserialize, Serialize};
+
+use crate::{Type, Value};
+
+#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Structure(Arc<BTreeMap<String, (Option<Value>, Type)>>);
+
+impl Structure {
+    pub fn new(map: BTreeMap<String, (Option<Value>, Type)>) -> Self {
+        Structure(Arc::new(map))
+    }
+
+    pub fn inner(&self) -> &BTreeMap<String, (Option<Value>, Type)> {
+        &self.0
+    }
+}
+
+impl Display for Structure {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        writeln!(f, "{{")?;
+
+        for (key, (value_option, r#type)) in self.0.as_ref() {
+            if let Some(value) = value_option {
+                writeln!(f, "  {key} <{}> = {value}", r#type)?;
+            } else {
+                writeln!(f, "  {key} <{}>", r#type)?;
+            }
+        }
+        write!(f, "}}")
+    }
+}
diff --git a/tests/structure.rs b/tests/structure.rs
index c0f5c93..c91094f 100644
--- a/tests/structure.rs
+++ b/tests/structure.rs
@@ -10,5 +10,5 @@ fn simple_structure() {
 
     btree_map.insert("x".to_string(), (Some(Value::Integer(0)), Type::Integer));
 
-    assert_eq!(Ok(Value::Structure(btree_map)), result);
+    assert_eq!(Ok(Value::Structure(Structure::new(btree_map))), result);
 }