diff --git a/crates/lang/src/builtins.rs b/crates/lang/src/builtins.rs
index 193aaab2..c2d084c8 100644
--- a/crates/lang/src/builtins.rs
+++ b/crates/lang/src/builtins.rs
@@ -21,6 +21,7 @@ pub const LIST: &str = "List";
 pub const NIL: &str = "Nil";
 pub const RESULT: &str = "Result";
 pub const STRING: &str = "String";
+pub const OPTION: &str = "Option";
 
 /// Build a prelude that can be injected
 /// into a compiler pipeline
@@ -224,6 +225,60 @@ pub fn prelude(id_gen: &IdGenerator) -> TypeInfo {
         ),
     );
 
+    // Option(value, none)
+    let option_value = generic_var(id_gen.next());
+    let option_none = generic_var(id_gen.next());
+
+    prelude.types.insert(
+        OPTION.to_string(),
+        TypeConstructor {
+            location: Span::empty(),
+            parameters: vec![option_value.clone(), option_none.clone()],
+            tipo: option(option_value, option_none),
+            module: "".to_string(),
+            public: true,
+        },
+    );
+
+    prelude.types_constructors.insert(
+        OPTION.to_string(),
+        vec!["Some".to_string(), "None".to_string()],
+    );
+
+    let some = generic_var(id_gen.next());
+    let none = generic_var(id_gen.next());
+    let _ = prelude.values.insert(
+        "Some".to_string(),
+        ValueConstructor::public(
+            function(vec![some.clone()], option(some, none)),
+            ValueConstructorVariant::Record {
+                module: "".into(),
+                name: "Some".to_string(),
+                field_map: None::<FieldMap>,
+                arity: 1,
+                location: Span::empty(),
+                constructors_count: 2,
+            },
+        ),
+    );
+
+    let some = generic_var(id_gen.next());
+    let none = generic_var(id_gen.next());
+    let _ = prelude.values.insert(
+        "None".to_string(),
+        ValueConstructor::public(
+            function(vec![none.clone()], option(some, none)),
+            ValueConstructorVariant::Record {
+                module: "".into(),
+                name: "None".to_string(),
+                field_map: None::<FieldMap>,
+                arity: 0,
+                location: Span::empty(),
+                constructors_count: 2,
+            },
+        ),
+    );
+
     prelude
 }
 
@@ -486,6 +541,15 @@ pub fn result(a: Arc<Type>, e: Arc<Type>) -> Arc<Type> {
     })
 }
 
+pub fn option(a: Arc<Type>, e: Arc<Type>) -> Arc<Type> {
+    Arc::new(Type::App {
+        public: true,
+        name: OPTION.to_string(),
+        module: "".to_string(),
+        args: vec![a, e],
+    })
+}
+
 pub fn function(args: Vec<Arc<Type>>, ret: Arc<Type>) -> Arc<Type> {
     Arc::new(Type::Fn { ret, args })
 }
diff --git a/examples/aiken_std/lib/aiken/context.ak b/examples/aiken_std/lib/aiken/context.ak
index 70a234bc..24cef8af 100644
--- a/examples/aiken_std/lib/aiken/context.ak
+++ b/examples/aiken_std/lib/aiken/context.ak
@@ -13,6 +13,9 @@ pub type ScriptPurpose {
   Certify(Certificate)
 }
 
+pub type Redeemer = 
+  Data
+
 pub type BoundValue(value) {
   NegativeInfinity
   Finite(value)
@@ -32,20 +35,21 @@ pub type Interval(value) {
 pub type Transaction {
   inputs: List(Input),
   reference_inputs: List(Input),
-  outputs: List(Nil),
+  outputs: List(Output),
   fee: Value,
   mint: Value,
   certificates: List(Certificate),
   withdrawals: List(Pair(StakeCredential, Int)),
   validity_range: Interval(Int),
-  extra_signatories: Nil,
-  redeemers: List(Nil),
+  extra_signatories: List(PublicKeyHash),
+  redeemers: List(Pair(ScriptPurpose, Redeemer)),
   datums: List(Pair(Hash(Data), Data)),
   id: TransactionId,
 }
 
-pub type TransactionId =
-  Hash(Transaction)
+pub type TransactionId = {
+  hash: Hash(Transaction)
+}
 
 pub type Input {
   output_reference: OutputReference,
@@ -60,17 +64,45 @@ pub type OutputReference {
 pub type PolicyId =
   ByteArray
 
-pub type StakeCredential =
-  Nil
+pub type StakeCredential = {
+  StakeHash(Credential)
+  StakePointer(Int, Int, Int)
+}
+
+pub type Credential = {
+  PublicKeyCredential(PublicKeyHash)
+  ScriptCredential(ScriptHash)
+}
 
 pub type VerificationKey =
   Nil
 
+pub type ScriptHash =
+  ByteArray
+
+pub type PublicKeyHash =
+  Hash(VerificationKey)
+
 pub type PoolId =
   Hash(VerificationKey)
 
-pub type Output =
-  Nil
+pub type Output = {
+  address: Address,
+  value: Value,
+  datum: DatumOption,
+  reference_script: Option(ScriptHash),
+}
+
+pub type Address = {
+  payment_credential: Credential,
+  stake_credential: Option(StakeCredential),
+}
+
+pub type DatumOption = {
+  NoDatum
+  DatumHash(Hash(Data))
+  Datum(Data)
+}
 
 pub type AssetName =
   ByteArray