diff --git a/src/value.rs b/src/value.rs
index 0d785aa..c1fdd2c 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -4,6 +4,7 @@ use std::{
     borrow::Cow,
     collections::BTreeMap,
     fmt::{Display, Write},
+    rc::Rc,
 };
 
 /// A Wisp value
@@ -13,7 +14,7 @@ pub enum Value<'a> {
     Vector(Vec<Self>),
     Map(BTreeMap<Self, Self>),
     Module(Module<'a>),
-    Function(Function),
+    Function(Function<'a>),
     Symbol(Symbol<'a>),
     Keyword(Cow<'a, str>),
     Bool(bool),
@@ -24,12 +25,28 @@ pub enum Value<'a> {
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Module<'a> {
-    members: BTreeMap<u64, Value<'a>>,
+    members: BTreeMap<u64, Rc<Value<'a>>>,
     symbol_table: BTreeMap<String, u64>,
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
-pub struct Function {}
+pub struct Function<'a> {
+    // TODO: bytecode
+    captures: Box<[Capture<'a>]>,
+    symbol_table: BTreeMap<Symbol<'a>, SymbolMapping>,
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Capture<'a> {
+    Reference(Rc<Value<'a>>),
+    Owned(Value<'a>),
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub enum SymbolMapping {
+    Local(u64),
+    Capture(u64),
+}
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Symbol<'a> {