diff --git a/ablescript/src/variables.rs b/ablescript/src/variables.rs
index 05157d46..cebd1024 100644
--- a/ablescript/src/variables.rs
+++ b/ablescript/src/variables.rs
@@ -87,6 +87,10 @@ impl BuiltinFunctio {
     pub fn call(&self, args: &[Rc<RefCell<Value>>]) -> Result<(), crate::error::ErrorKind> {
         (self.function)(args)
     }
+
+    pub fn fn_addr(&self) -> usize {
+        Rc::as_ptr(&self.function) as *const () as _
+    }
 }
 
 impl std::fmt::Debug for BuiltinFunctio {
@@ -106,7 +110,7 @@ impl PartialEq for BuiltinFunctio {
 
 impl Hash for BuiltinFunctio {
     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        (Rc::as_ptr(&self.function) as *const () as usize).hash(state);
+        self.fn_addr().hash(state);
         self.arity.hash(state);
     }
 }
@@ -180,7 +184,7 @@ impl Value {
                         .sum::<i32>()
                         + body.len() as i32
                 }
-                Functio::Builtin(_) => todo!(),
+                Functio::Builtin(b) => b.fn_addr() as _,
                 Functio::Chain { functios, kind } => {
                     let (lf, rf) = *functios;
                     Value::Functio(lf).into_i32()
@@ -269,7 +273,7 @@ impl Value {
 
                     Value::Int((params + body) % 3 - 1).into_abool()
                 }
-                Functio::Builtin(_) => todo!(),
+                Functio::Builtin(b) => Value::Bool(b.fn_addr() % b.arity == 0).into_abool(),
                 Functio::Chain { functios, kind } => {
                     let (lhs, rhs) = *functios;
                     match kind {
@@ -439,7 +443,22 @@ impl Value {
                     );
                     cart
                 }
-                Functio::Builtin(_) => todo!(),
+                Functio::Builtin(b) => {
+                    let mut cart = HashMap::new();
+                    cart.insert(
+                        Value::Str("addr".to_owned()),
+                        Rc::new(RefCell::new(Value::Cart(
+                            Value::Int(b.fn_addr() as _).into_cart(),
+                        ))),
+                    );
+
+                    cart.insert(
+                        Value::Str("arity".to_owned()),
+                        Rc::new(RefCell::new(Value::Int(b.arity as _))),
+                    );
+
+                    cart
+                }
                 Functio::Chain { functios, kind } => {
                     let (lhs, rhs) = *functios;
                     match kind {
@@ -489,7 +508,9 @@ impl Value {
                     tape_len,
                 } => (instructions.len() + tape_len) as _,
                 Functio::Able { params, body } => (params.len() + format!("{:?}", body).len()) as _,
-                Functio::Builtin(_) => todo!(),
+                Functio::Builtin(b) => {
+                    (std::mem::size_of_val(b.function.as_ref()) + b.arity) as i32
+                }
                 Functio::Chain { functios, kind } => {
                     let (lhs, rhs) = *functios.clone();
                     match kind {