diff --git a/recapn-rpc/src/gen/capnp/rpc.capnp.rs b/recapn-rpc/src/gen/capnp/rpc.capnp.rs
index e87832e..81f75d2 100644
--- a/recapn-rpc/src/gen/capnp/rpc.capnp.rs
+++ b/recapn-rpc/src/gen/capnp/rpc.capnp.rs
@@ -105,7 +105,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Message>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const ABORT: _p::VariantDescriptor<_p::Struct<Exception>> = _p::VariantDescriptor::<
@@ -117,7 +117,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Exception>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const CALL: _p::VariantDescriptor<_p::Struct<Call>> = _p::VariantDescriptor::<
@@ -129,7 +129,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Call>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const RETURN: _p::VariantDescriptor<_p::Struct<Return>> = _p::VariantDescriptor::<
@@ -141,7 +141,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Return>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const FINISH: _p::VariantDescriptor<_p::Struct<Finish>> = _p::VariantDescriptor::<
@@ -153,7 +153,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Finish>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const RESOLVE: _p::VariantDescriptor<_p::Struct<Resolve>> = _p::VariantDescriptor::<
@@ -165,7 +165,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Resolve>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const RELEASE: _p::VariantDescriptor<_p::Struct<Release>> = _p::VariantDescriptor::<
@@ -177,7 +177,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Release>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const OBSOLETE_SAVE: _p::VariantDescriptor<_p::AnyPtr> = _p::VariantDescriptor::<
@@ -189,7 +189,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::AnyPtr> {
             slot: 0u32,
-            default: _p::ptr::PtrReader::null(),
+            default: None,
         },
     };
     const BOOTSTRAP: _p::VariantDescriptor<_p::Struct<Bootstrap>> = _p::VariantDescriptor::<
@@ -201,7 +201,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Bootstrap>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const OBSOLETE_DELETE: _p::VariantDescriptor<_p::AnyPtr> = _p::VariantDescriptor::<
@@ -213,7 +213,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::AnyPtr> {
             slot: 0u32,
-            default: _p::ptr::PtrReader::null(),
+            default: None,
         },
     };
     const PROVIDE: _p::VariantDescriptor<_p::Struct<Provide>> = _p::VariantDescriptor::<
@@ -225,7 +225,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Provide>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const ACCEPT: _p::VariantDescriptor<_p::Struct<Accept>> = _p::VariantDescriptor::<
@@ -237,7 +237,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Accept>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const JOIN: _p::VariantDescriptor<_p::Struct<Join>> = _p::VariantDescriptor::<
@@ -249,7 +249,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Join>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const DISEMBARGO: _p::VariantDescriptor<_p::Struct<Disembargo>> = _p::VariantDescriptor::<
@@ -261,7 +261,7 @@ impl Message {
         },
         field: _p::Descriptor::<_p::Struct<Disembargo>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
 }
@@ -1084,7 +1084,7 @@ impl Bootstrap {
         _p::AnyPtr,
     > {
         slot: 0u32,
-        default: _p::ptr::PtrReader::null(),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> bootstrap::Reader<'p, T> {
@@ -1240,7 +1240,7 @@ impl Call {
         _p::Struct<MessageTarget>,
     > {
         slot: 0u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const INTERFACE_ID: _p::Descriptor<u64> = _p::Descriptor::<u64> {
         slot: 1u32,
@@ -1254,7 +1254,7 @@ impl Call {
         _p::Struct<Payload>,
     > {
         slot: 1u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const SEND_RESULTS_TO: _p::Descriptor<_p::Group<call::SendResultsTo>> = ();
     const ALLOW_THIRD_PARTY_TAIL_CALL: _p::Descriptor<bool> = _p::Descriptor::<bool> {
@@ -1560,7 +1560,7 @@ pub mod call {
             },
             field: _p::Descriptor::<_p::AnyPtr> {
                 slot: 2u32,
-                default: _p::ptr::PtrReader::null(),
+                default: None,
             },
         };
     }
@@ -1850,7 +1850,7 @@ impl Return {
         },
         field: _p::Descriptor::<_p::Struct<Payload>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const EXCEPTION: _p::VariantDescriptor<_p::Struct<Exception>> = _p::VariantDescriptor::<
@@ -1862,7 +1862,7 @@ impl Return {
         },
         field: _p::Descriptor::<_p::Struct<Exception>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const CANCELED: _p::VariantDescriptor<()> = _p::VariantDescriptor::<()> {
@@ -1902,7 +1902,7 @@ impl Return {
         },
         field: _p::Descriptor::<_p::AnyPtr> {
             slot: 0u32,
-            default: _p::ptr::PtrReader::null(),
+            default: None,
         },
     };
 }
@@ -2491,7 +2491,7 @@ impl Resolve {
         },
         field: _p::Descriptor::<_p::Struct<CapDescriptor>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const EXCEPTION: _p::VariantDescriptor<_p::Struct<Exception>> = _p::VariantDescriptor::<
@@ -2503,7 +2503,7 @@ impl Resolve {
         },
         field: _p::Descriptor::<_p::Struct<Exception>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
 }
@@ -2890,7 +2890,7 @@ impl Disembargo {
         _p::Struct<MessageTarget>,
     > {
         slot: 0u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const CONTEXT: _p::Descriptor<_p::Group<disembargo::Context>> = ();
 }
@@ -3387,11 +3387,11 @@ impl Provide {
         _p::Struct<MessageTarget>,
     > {
         slot: 0u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const RECIPIENT: _p::Descriptor<_p::AnyPtr> = _p::Descriptor::<_p::AnyPtr> {
         slot: 1u32,
-        default: _p::ptr::PtrReader::null(),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> provide::Reader<'p, T> {
@@ -3561,7 +3561,7 @@ impl Accept {
     };
     const PROVISION: _p::Descriptor<_p::AnyPtr> = _p::Descriptor::<_p::AnyPtr> {
         slot: 0u32,
-        default: _p::ptr::PtrReader::null(),
+        default: None,
     };
     const EMBARGO: _p::Descriptor<bool> = _p::Descriptor::<bool> {
         slot: 32u32,
@@ -3721,11 +3721,11 @@ impl Join {
         _p::Struct<MessageTarget>,
     > {
         slot: 0u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const KEY_PART: _p::Descriptor<_p::AnyPtr> = _p::Descriptor::<_p::AnyPtr> {
         slot: 1u32,
-        default: _p::ptr::PtrReader::null(),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> join::Reader<'p, T> {
@@ -3903,7 +3903,7 @@ impl MessageTarget {
         },
         field: _p::Descriptor::<_p::Struct<PromisedAnswer>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
 }
@@ -4142,15 +4142,13 @@ impl _p::ty::Struct for Payload {
 impl Payload {
     const CONTENT: _p::Descriptor<_p::AnyPtr> = _p::Descriptor::<_p::AnyPtr> {
         slot: 0u32,
-        default: _p::ptr::PtrReader::null(),
+        default: None,
     };
     const CAP_TABLE: _p::Descriptor<_p::List<_p::Struct<CapDescriptor>>> = _p::Descriptor::<
         _p::List<_p::Struct<CapDescriptor>>,
     > {
         slot: 1u32,
-        default: _p::ListReader::empty(
-            _p::ElementSize::size_of::<_p::Struct<CapDescriptor>>(),
-        ),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> payload::Reader<'p, T> {
@@ -4358,7 +4356,7 @@ impl CapDescriptor {
         },
         field: _p::Descriptor::<_p::Struct<PromisedAnswer>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
     const THIRD_PARTY_HOSTED: _p::VariantDescriptor<
@@ -4370,7 +4368,7 @@ impl CapDescriptor {
         },
         field: _p::Descriptor::<_p::Struct<ThirdPartyCapDescriptor>> {
             slot: 0u32,
-            default: _p::StructReader::empty(),
+            default: None,
         },
     };
 }
@@ -4806,9 +4804,7 @@ impl PromisedAnswer {
         _p::List<_p::Struct<promised_answer::Op>>,
     > {
         slot: 0u32,
-        default: _p::ListReader::empty(
-            _p::ElementSize::size_of::<_p::Struct<promised_answer::Op>>(),
-        ),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> promised_answer::Reader<'p, T> {
@@ -5205,7 +5201,7 @@ impl _p::ty::Struct for ThirdPartyCapDescriptor {
 impl ThirdPartyCapDescriptor {
     const ID: _p::Descriptor<_p::AnyPtr> = _p::Descriptor::<_p::AnyPtr> {
         slot: 0u32,
-        default: _p::ptr::PtrReader::null(),
+        default: None,
     };
     const VINE_ID: _p::Descriptor<u32> = _p::Descriptor::<u32> {
         slot: 0u32,
@@ -5367,7 +5363,7 @@ impl _p::ty::Struct for Exception {
 impl Exception {
     const REASON: _p::Descriptor<_p::Text> = _p::Descriptor::<_p::Text> {
         slot: 0u32,
-        default: _p::text::Reader::empty(),
+        default: None,
     };
     const OBSOLETE_IS_CALLERS_FAULT: _p::Descriptor<bool> = _p::Descriptor::<bool> {
         slot: 0u32,
@@ -5385,7 +5381,7 @@ impl Exception {
     };
     const TRACE: _p::Descriptor<_p::Text> = _p::Descriptor::<_p::Text> {
         slot: 1u32,
-        default: _p::text::Reader::empty(),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> exception::Reader<'p, T> {
diff --git a/recapn/src/any.rs b/recapn/src/any.rs
index d3d5c17..29c74d0 100644
--- a/recapn/src/any.rs
+++ b/recapn/src/any.rs
@@ -92,10 +92,6 @@ impl<T> IntoFamily for AnyPtr<T> {
     type Family = AnyPtr;
 }
 
-impl ty::Value for AnyPtr {
-    type Default = ptr::PtrReader<'static, Empty>;
-}
-
 impl ty::ListValue for AnyPtr {
     const ELEMENT_SIZE: list::ElementSize = list::ElementSize::Pointer;
 }
@@ -583,10 +579,6 @@ impl<T> IntoFamily for AnyStruct<T> {
     type Family = AnyStruct;
 }
 
-impl ty::Value for AnyStruct {
-    type Default = ptr::StructReader<'static, Empty>;
-}
-
 impl ty::DynListValue for AnyStruct {
     const PTR_ELEMENT_SIZE: crate::ptr::PtrElementSize = crate::ptr::PtrElementSize::InlineComposite;
 }
@@ -900,9 +892,6 @@ impl<T> IntoFamily for AnyList<T> {
     type Family = AnyList;
 }
 
-impl ty::Value for AnyList {
-    type Default = ptr::ListReader<'static, Empty>;
-}
 impl ty::ListValue for AnyList {
     const ELEMENT_SIZE: list::ElementSize = list::ElementSize::Pointer;
 }
diff --git a/recapn/src/data.rs b/recapn/src/data.rs
index 4476cda..9d69148 100644
--- a/recapn/src/data.rs
+++ b/recapn/src/data.rs
@@ -22,9 +22,6 @@ impl Sealed for Data {}
 impl<T> IntoFamily for Data<T> {
     type Family = Data;
 }
-impl ty::Value for Data {
-    type Default = Reader<'static>;
-}
 impl ty::ListValue for Data {
     const ELEMENT_SIZE: ElementSize = ElementSize::Pointer;
 }
diff --git a/recapn/src/field.rs b/recapn/src/field.rs
index cfb0b8b..e0e76a4 100644
--- a/recapn/src/field.rs
+++ b/recapn/src/field.rs
@@ -37,7 +37,7 @@
 //! lifetimes respectively. So `&'b ptr::StructReader<'p, T>` could be extended to
 //! `&'borrow ptr::StructReader<'pointer, T>`.
 
-use core::convert::TryFrom;
+use core::convert::{TryFrom, Infallible as Never};
 use core::marker::PhantomData;
 use core::str::Utf8Error;
 
@@ -272,9 +272,24 @@ pub type VariantMut<'b, 'p, T, V> = <V as FieldType>::VariantAccessor<StructBuil
 
 pub type VariantOwned<'p, T, V> = <V as FieldType>::VariantAccessor<ptr::StructBuilder<'p, T>>;
 
+/// A trait used to specify that a type is used to represent a Cap'n Proto value.
+pub trait Value: 'static {
+    type Default;
+}
+
+/// A trait used to specify that a type is backed by a pointer field. This enables generic pointers
+/// in generated code.
+pub trait PtrValue: 'static {
+    type Default;
+}
+
+impl<T: PtrValue> Value for T {
+    type Default = Option<<T as PtrValue>::Default>;
+}
+
 /// Describes a value in a "slot" in a struct. This does not include groups or void, which don't
 /// have an associated default value or slot.
-pub struct FieldInfo<V: ty::Value> {
+pub struct FieldInfo<V: Value> {
     pub slot: u32,
     pub default: V::Default,
 }
@@ -304,7 +319,7 @@ pub struct Struct<S: ty::Struct> {
 }
 
 impl<S: ty::Struct> Sealed for Struct<S> {}
-impl<S: ty::Struct> ty::Value for Struct<S> {
+impl<S: ty::Struct> PtrValue for Struct<S> {
     type Default = ptr::StructReader<'static>;
 }
 impl<S: ty::Struct> ListValue for Struct<S> {
@@ -339,9 +354,9 @@ pub struct Capability<C: ty::Capability> {
 }
 
 impl<C: ty::Capability> Sealed for Capability<C> {}
-impl<C: ty::Capability> ty::Value for Capability<C> {
+impl<C: ty::Capability> PtrValue for Capability<C> {
     /// Capabilities don't have defaults
-    type Default = ();
+    type Default = Never;
 }
 impl<C: ty::Capability> ListValue for Capability<C> {
     const ELEMENT_SIZE: ElementSize = ElementSize::Pointer;
@@ -353,7 +368,7 @@ pub struct Enum<E: ty::Enum> {
 }
 
 impl<E: ty::Enum> Sealed for Enum<E> {}
-impl<E: ty::Enum> ty::Value for Enum<E> {
+impl<E: ty::Enum> Value for Enum<E> {
     type Default = E;
 }
 impl<E: ty::Enum> ListValue for Enum<E> {
@@ -454,7 +469,7 @@ impl<'b, 'p, T: Table, G: FieldGroup> VoidVariant<Group<G>, StructBuilder<'b, 'p
     }
 }
 
-pub struct DataField<D: ty::Value, Repr> {
+pub struct DataField<D: Value, Repr> {
     descriptor: &'static FieldInfo<D>,
     repr: Repr,
 }
@@ -471,7 +486,7 @@ impl<'b, 'p, T: Table, D: Data> DataField<D, StructBuilder<'b, 'p, T>> {
     }
 }
 
-pub struct DataVariant<D: ty::Value, Repr> {
+pub struct DataVariant<D: Value, Repr> {
     descriptor: &'static FieldInfo<D>,
     variant: &'static VariantInfo,
     repr: Repr,
@@ -641,7 +656,7 @@ impl<'b, 'p, T: Table, E: ty::Enum> DataVariant<Enum<E>, StructBuilder<'b, 'p, T
     }
 }
 
-pub struct PtrField<V: ty::Value, Repr> {
+pub struct PtrField<V: PtrValue, Repr> {
     descriptor: &'static FieldInfo<V>,
     repr: Repr,
 }
@@ -650,7 +665,7 @@ pub type PtrFieldReader<'b, 'p, T, V> = PtrField<V, StructReader<'b, 'p, T>>;
 pub type PtrFieldBuilder<'b, 'p, T, V> = PtrField<V, StructBuilder<'b, 'p, T>>;
 pub type PtrFieldOwner<'p, T, V> = PtrField<V, OwnedStructBuilder<'p, T>>;
 
-impl<'b, 'p, T: Table, V: ty::Value> PtrFieldReader<'b, 'p, T, V> {
+impl<'b, 'p, T: Table, V: PtrValue> PtrFieldReader<'b, 'p, T, V> {
     #[inline]
     fn raw_ptr(&self) -> ptr::PtrReader<'p, T> {
         self.repr.ptr_field(self.descriptor.slot as u16)
@@ -667,7 +682,7 @@ impl<'b, 'p, T: Table, V: ty::Value> PtrFieldReader<'b, 'p, T, V> {
     }
 }
 
-impl<'b, 'p, T: Table, V: ty::Value> PtrFieldBuilder<'b, 'p, T, V> {
+impl<'b, 'p, T: Table, V: PtrValue> PtrFieldBuilder<'b, 'p, T, V> {
     /// Create a new field builder "by reference". This allows a field builder to be reused
     /// as many builder functions consume the builder.
     #[inline]
@@ -725,7 +740,7 @@ impl<'b, 'p, T: Table, V: ty::Value> PtrFieldBuilder<'b, 'p, T, V> {
     }
 }
 
-impl<'p, T: Table, V: ty::Value> PtrFieldOwner<'p, T, V> {
+impl<'p, T: Table, V: PtrValue> PtrFieldOwner<'p, T, V> {
     /// Create a new field builder "by reference". This allows a field builder to be reused
     /// as many builder functions consume the builder.
     #[inline]
@@ -784,7 +799,7 @@ impl<'p, T: Table, V: ty::Value> PtrFieldOwner<'p, T, V> {
 }
 
 /// A base type for accessing union variant fields.
-pub struct PtrVariant<V: ty::Value, Repr> {
+pub struct PtrVariant<V: PtrValue, Repr> {
     descriptor: &'static FieldInfo<V>,
     variant: &'static VariantInfo,
     repr: Repr,
@@ -794,7 +809,7 @@ pub type PtrVariantReader<'b, 'p, T, V> = PtrVariant<V, StructReader<'b, 'p, T>>
 pub type PtrVariantBuilder<'b, 'p, T, V> = PtrVariant<V, StructBuilder<'b, 'p, T>>;
 pub type PtrVariantOwner<'p, T, V> = PtrVariant<V, OwnedStructBuilder<'p, T>>;
 
-impl<'b, 'p, T: Table, V: ty::Value> PtrVariantReader<'b, 'p, T, V> {
+impl<'b, 'p, T: Table, V: PtrValue> PtrVariantReader<'b, 'p, T, V> {
     /// Returns a bool indicating whether or not this field is set in the union
     #[inline]
     pub fn is_set(&self) -> bool {
@@ -803,8 +818,12 @@ impl<'b, 'p, T: Table, V: ty::Value> PtrVariantReader<'b, 'p, T, V> {
     }
 
     #[inline]
-    fn raw_ptr(&self) -> Option<ptr::PtrReader<'b, T>> {
-        self.is_set().then(|| self.repr.ptr_field(self.descriptor.slot as u16))
+    fn raw_ptr_or_null(&self) -> ptr::PtrReader<'b, T> {
+        if self.is_set() {
+            self.repr.ptr_field(self.descriptor.slot as u16)
+        } else {
+            ptr::PtrReader::null().imbue_from(self.repr)
+        }
     }
 
     #[inline]
@@ -822,7 +841,7 @@ impl<'b, 'p, T: Table, V: ty::Value> PtrVariantReader<'b, 'p, T, V> {
     }
 }
 
-impl<'b, 'p, T: Table, V: ty::Value> PtrVariantBuilder<'b, 'p, T, V> {
+impl<'b, 'p, T: Table, V: PtrValue> PtrVariantBuilder<'b, 'p, T, V> {
     /// Returns a bool indicating whether or not this field is set in the union
     #[inline]
     pub fn is_set(&self) -> bool {
@@ -907,7 +926,7 @@ impl<'b, 'p, T: Table, V: ty::Value> PtrVariantBuilder<'b, 'p, T, V> {
     }
 }
 
-impl<'p, T: Table, V: ty::Value> PtrVariantOwner<'p, T, V> {
+impl<'p, T: Table, V: PtrValue> PtrVariantOwner<'p, T, V> {
     /// Returns a bool indicating whether or not this field is set in the union
     #[inline]
     pub fn is_set(&self) -> bool {
@@ -942,6 +961,10 @@ macro_rules! field_type_items {
 
 // impls for list
 
+impl<V: 'static> PtrValue for List<V> {
+    type Default = ptr::ListReader<'static>;
+}
+
 impl<V: 'static> FieldType for List<V> {
     field_type_items!{}
 }
@@ -952,10 +975,14 @@ where
 {
     #[inline]
     fn default(&self) -> list::Reader<'static, V, T> {
-        let default = &self.descriptor.default;
-        assert!(default.element_size().upgradable_to(V::PTR_ELEMENT_SIZE));
+        match &self.descriptor.default {
+            Some(default) => {
+                debug_assert!(default.element_size().upgradable_to(V::PTR_ELEMENT_SIZE));
 
-        List::new(default.clone().imbue_from(self.repr))
+                List::new(default.clone().imbue_from(self.repr))
+            }
+            None => List::empty().imbue_from(self.repr)
+        }
     }
 
     #[inline]
@@ -1017,10 +1044,14 @@ where
 impl<'b, 'p, T: Table, V: ty::DynListValue> PtrVariantReader<'b, 'p, T, List<V>> {
     #[inline]
     fn default(&self) -> list::Reader<'static, V, T> {
-        let default = &self.descriptor.default;
-        assert!(default.element_size().upgradable_to(V::PTR_ELEMENT_SIZE));
+        match &self.descriptor.default {
+            Some(default) => {
+                debug_assert!(default.element_size().upgradable_to(V::PTR_ELEMENT_SIZE));
 
-        List::new(default.clone().imbue_from(self.repr))
+                List::new(default.clone().imbue_from(self.repr))
+            }
+            None => List::empty().imbue_from(self.repr)
+        }
     }
 
     #[inline]
@@ -1060,9 +1091,14 @@ impl<'b, 'p, T: Table, V: ty::ListValue> PtrFieldBuilder<'b, 'p, T, List<V>> {
         match self.into_raw_build_ptr().to_list_mut(Some(V::ELEMENT_SIZE)) {
             Ok(ptr) => List::new(ptr),
             Err((_, ptr)) => {
-                assert_eq!(default.element_size(), V::ELEMENT_SIZE);
-                let mut new_list = ptr.init_list(V::ELEMENT_SIZE, default.len());
-                new_list.try_copy_from(default, UnwrapErrors).unwrap();
+                let new_list = if let Some(default) = default {
+                    debug_assert_eq!(default.element_size(), V::ELEMENT_SIZE);
+                    let mut new_list = ptr.init_list(V::ELEMENT_SIZE, default.len());
+                    new_list.try_copy_from(default, UnwrapErrors).unwrap();
+                    new_list
+                } else {
+                    ptr.init_list(V::ELEMENT_SIZE, ElementCount::ZERO)
+                };
                 List::new(new_list)
             }
         }
@@ -1124,7 +1160,7 @@ impl<'b, 'p, T: Table> PtrFieldBuilder<'b, 'p, T, List<AnyStruct>> {
             .to_list_mut(expected_size.map(ElementSize::InlineComposite))
         {
             Ok(ptr) => ptr,
-            Err((_, ptr)) => {
+            Err((_, ptr)) => if let Some(default) = default {
                 let default_size = default.element_size();
                 let size = match expected_size {
                     Some(e) => {
@@ -1137,6 +1173,9 @@ impl<'b, 'p, T: Table> PtrFieldBuilder<'b, 'p, T, List<AnyStruct>> {
                 let mut builder = ptr.init_list(size, default.len());
                 builder.try_copy_from(default, UnwrapErrors).unwrap();
                 builder
+            } else {
+                let s = ElementSize::InlineComposite(expected_size.unwrap_or(StructSize::EMPTY));
+                ptr.init_list(s, ElementCount::ZERO)
             }
         };
         List::new(ptr)
@@ -1165,7 +1204,7 @@ impl<S: ty::Struct> FieldType for Struct<S> {
 impl<S: ty::Struct, Repr> PtrField<Struct<S>, Repr> {
     #[inline]
     fn default_ptr(&self) -> ptr::StructReader<'static> {
-        self.descriptor.default.clone()
+        self.descriptor.default.clone().unwrap_or_else(ptr::StructReader::empty)
     }
 
     /// Returns the default value of the field
@@ -1229,7 +1268,9 @@ where
             Ok(ptr) => ptr,
             Err((_, ptr)) => {
                 let mut builder = ptr.init_struct(S::SIZE);
-                builder.copy_with_caveats(default, false);
+                if let Some(default) = default {
+                    builder.copy_with_caveats(default, false);
+                }
                 builder
             }
         };
@@ -1275,21 +1316,39 @@ where
     }
 }
 
+impl<S: ty::Struct, Repr> PtrVariant<Struct<S>, Repr> {
+    #[inline]
+    fn default_ptr(&self) -> ptr::StructReader<'static> {
+        self.descriptor.default.clone().unwrap_or_else(ptr::StructReader::empty)
+    }
+
+    /// Returns the default value of the field
+    #[inline]
+    pub fn default(&self) -> S::Reader<'static, Empty> {
+        ty::StructReader::from_ptr(self.default_ptr())
+    }
+}
+
 impl<'b, 'p: 'b, T: Table + 'p, S> PtrVariantReader<'b, 'p, T, Struct<S>>
 where
     S: ty::Struct,
 {
     #[inline]
-    fn default(&self) -> S::Reader<'b, T> {
-        self.descriptor.default.clone().imbue_from(self.repr).into()
+    fn default_imbued_ptr(&self) -> ptr::StructReader<'static, T> {
+        self.descriptor
+            .default
+            .clone()
+            .unwrap_or_else(ptr::StructReader::empty)
+            .imbue_from(self.repr)
     }
 
     #[inline]
     pub fn get_or_default(&self) -> S::Reader<'b, T> {
-        self.try_get_option()
-            .ok()
-            .flatten()
-            .unwrap_or_else(|| self.default())
+        let ptr = match self.raw_ptr_or_null().to_struct() {
+            Ok(Some(ptr)) => ptr,
+            _ => self.default_imbued_ptr(),
+        };
+        ty::StructReader::from_ptr(ptr)
     }
 
     #[inline]
@@ -1299,8 +1358,12 @@ where
 
     #[inline]
     pub fn try_get(&self) -> Result<S::Reader<'b, T>> {
-        self.try_get_option()
-            .map(|op| op.unwrap_or_else(|| self.default()))
+        let ptr = match self.raw_ptr_or_null().to_struct() {
+            Ok(Some(ptr)) => ptr,
+            Ok(None) => self.default_imbued_ptr(),
+            Err(err) => return Err(err),
+        };
+        Ok(ty::StructReader::from_ptr(ptr))
     }
 
     #[inline]
@@ -1353,6 +1416,10 @@ where
     }
 }
 
+impl PtrValue for text::Text {
+    type Default = text::Reader<'static>;
+}
+
 impl FieldType for text::Text {
     field_type_items!{}
 }
@@ -1361,7 +1428,7 @@ impl<Repr> PtrField<text::Text, Repr> {
     /// Returns the default value of the field
     #[inline]
     pub fn default(&self) -> text::Reader<'static> {
-        self.descriptor.default
+        self.descriptor.default.unwrap_or_else(text::Reader::empty)
     }
 }
 
@@ -1412,7 +1479,7 @@ impl<'b, 'p: 'b, T: Table + 'p> PtrFieldBuilder<'b, 'p, T, text::Text> {
     /// existing value, the default is set instead.
     #[inline]
     pub fn get(self) -> text::Builder<'b> {
-        let default = self.descriptor.default;
+        let default = self.descriptor.default.unwrap_or_else(text::Reader::empty);
         let blob = match self.into_raw_build_ptr().to_blob_mut() {
             Ok(b) => b,
             Err((_, ptr)) => ptr.set_blob(default.into()),
@@ -1475,6 +1542,10 @@ impl<'b, 'p: 'b, T: Table + 'p> PtrVariantBuilder<'b, 'p, T, text::Text> {
 
 }
 
+impl PtrValue for data::Data {
+    type Default = data::Reader<'static>;
+}
+
 impl FieldType for data::Data {
     field_type_items!{}
 }
@@ -1483,7 +1554,7 @@ impl<Repr> PtrField<data::Data, Repr> {
     /// Returns the default value of the field
     #[inline]
     pub fn default(&self) -> data::Reader<'static> {
-        self.descriptor.default.clone().into()
+        self.descriptor.default.unwrap_or_else(data::Reader::empty)
     }
 }
 
@@ -1519,7 +1590,7 @@ impl<'b, 'p: 'b, T: Table + 'p> PtrFieldBuilder<'b, 'p, T, data::Data> {
     /// existing value, the default is set instead.
     #[inline]
     pub fn get(self) -> data::Builder<'b> {
-        let default = self.descriptor.default;
+        let default = self.descriptor.default.unwrap_or_else(data::Reader::empty);
         match self.into_raw_build_ptr().to_blob_mut() {
             Ok(data) => data,
             Err((_, ptr)) => ptr.set_blob(default.into()),
@@ -1570,6 +1641,10 @@ impl<'b, 'p: 'b, T: Table + 'p> PtrVariantBuilder<'b, 'p, T, data::Data> {
     // TODO accessors
 }
 
+impl PtrValue for AnyPtr {
+    type Default = ptr::PtrReader<'static, Empty>;
+}
+
 impl FieldType for AnyPtr {
     field_type_items!();
 }
@@ -1582,6 +1657,10 @@ impl<'b, 'p: 'b, T: Table + 'p> PtrVariantBuilder<'b, 'p, T, AnyPtr> {
     // TODO accessors
 }
 
+impl PtrValue for AnyStruct {
+    type Default = ptr::StructReader<'static, Empty>;
+}
+
 impl FieldType for AnyStruct {
     field_type_items!{}
 }
@@ -1590,7 +1669,7 @@ impl<Repr> PtrField<AnyStruct, Repr> {
     /// Returns the default value of the field
     #[inline]
     fn default_ptr(&self) -> ptr::StructReader<'static> {
-        self.descriptor.default.clone()
+        self.descriptor.default.clone().unwrap_or_else(ptr::StructReader::empty)
     }
 
     /// Returns the default value of the field
@@ -1644,6 +1723,10 @@ impl<'b, 'p: 'b, T: Table + 'p> PtrVariantBuilder<'b, 'p, T, AnyStruct> {
     // TODO accessors
 }
 
+impl PtrValue for AnyList {
+    type Default = ptr::ListReader<'static, Empty>;
+}
+
 impl FieldType for AnyList {
     field_type_items!{}
 }
@@ -1652,7 +1735,10 @@ impl<Repr> PtrField<AnyList, Repr> {
     /// Returns the default value of the field
     #[inline]
     fn default_ptr(&self) -> ptr::ListReader<'static> {
-        self.descriptor.default.clone()
+        self.descriptor
+            .default
+            .clone()
+            .unwrap_or_else(|| ptr::ListReader::empty(ElementSize::Void))
     }
 
     /// Returns the default value of the field
diff --git a/recapn/src/ptr.rs b/recapn/src/ptr.rs
index 66480ea..387eca5 100644
--- a/recapn/src/ptr.rs
+++ b/recapn/src/ptr.rs
@@ -4,6 +4,7 @@ use crate::alloc::{
     AllocLen, Segment, SegmentLen, SegmentOffset, SegmentPtr, SegmentRef, SignedSegmentOffset, Word
 };
 use crate::arena::{SegmentId, SegmentWithId, ReadArena, BuildArena, ArenaSegment};
+use crate::field;
 use crate::internal::Sealed;
 use crate::message::ReadLimiter;
 use crate::num::u29;
@@ -25,7 +26,7 @@ pub use crate::data::ptr::{Reader as DataReader, Builder as DataBuilder};
 pub use crate::text::ptr::{Reader as TextReader, Builder as TextBuilder};
 
 /// A field type that can be found in the data section of a struct.
-pub trait Data: ty::Value<Default = Self> + ty::ListValue + Default + Copy + Sealed + 'static {
+pub trait Data: field::Value<Default = Self> + ty::ListValue + Default + Copy + Sealed + 'static {
     unsafe fn read(ptr: *const u8, len: u32, slot: usize, default: Self) -> Self;
     unsafe fn read_unchecked(ptr: *const u8, slot: usize, default: Self) -> Self;
 
diff --git a/recapn/src/text.rs b/recapn/src/text.rs
index 16a500d..36df54f 100644
--- a/recapn/src/text.rs
+++ b/recapn/src/text.rs
@@ -38,9 +38,6 @@ pub type Reader<'a> = Text<ptr::Reader<'a>>;
 pub type Builder<'a> = Text<ptr::Builder<'a>>;
 
 impl Sealed for Text {}
-impl ty::Value for Text {
-    type Default = Reader<'static>;
-}
 impl ty::ListValue for Text {
     const ELEMENT_SIZE: ElementSize = ElementSize::Pointer;
 }
diff --git a/recapn/src/ty.rs b/recapn/src/ty.rs
index 8c41a29..84d1e58 100644
--- a/recapn/src/ty.rs
+++ b/recapn/src/ty.rs
@@ -200,11 +200,6 @@ impl<'a, S: Struct, T: Table> ReadPtr<any::PtrReader<'a, T>> for field::Struct<S
     }
 }
 
-/// A trait used to specify that a type is used to represent a Cap'n Proto value.
-pub trait Value: Sealed + 'static {
-    type Default;
-}
-
 /// A type representing a fixed size Cap'n Proto value that can be stored in a list.
 ///
 /// Note not every type that be stored in a list will implement this trait. Dynamically
@@ -214,7 +209,7 @@ pub trait ListValue: DynListValue {
     const ELEMENT_SIZE: ElementSize;
 }
 
-pub trait DynListValue: Value {
+pub trait DynListValue: 'static {
     const PTR_ELEMENT_SIZE: ptr::PtrElementSize;
 }
 impl<T: ListValue> DynListValue for T {
@@ -241,7 +236,7 @@ pub type Float64 = f64;
 macro_rules! impl_value {
     ($ty:ty, $size:ident) => {
         impl Sealed for $ty {}
-        impl Value for $ty {
+        impl field::Value for $ty {
             type Default = Self;
         }
         impl ListValue for $ty {
@@ -263,9 +258,6 @@ impl_value!(Int64, EightBytes);
 impl_value!(Float32, FourBytes);
 impl_value!(Float64, EightBytes);
 
-impl<V: 'static> Value for List<V> {
-    type Default = ptr::ListReader<'static>;
-}
 impl<V: 'static> ListValue for List<V> {
     const ELEMENT_SIZE: list::ElementSize = list::ElementSize::Pointer;
 }
diff --git a/recapnc/src/gen/capnp/schema.capnp.rs b/recapnc/src/gen/capnp/schema.capnp.rs
index f693e14..b28beb8 100644
--- a/recapnc/src/gen/capnp/schema.capnp.rs
+++ b/recapnc/src/gen/capnp/schema.capnp.rs
@@ -10,18 +10,18 @@ _p::generate_file! {
         size: { data: 5, ptrs: 6 },
         fields: {
             ID, id, id_mut, u64 = { slot: 0, default: 0 },
-            DISPLAY_NAME, display_name, display_name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+            DISPLAY_NAME, display_name, display_name_mut, _p::Text = { slot: 0, default: None },
             DISPLAY_NAME_PREFIX_LENGTH, display_name_prefix_length, display_name_prefix_length_mut, u32 = { slot: 2, default: 0 },
             SCOPE_ID, scope_id, scope_id_mut, u64 = { slot: 2, default: 0 },
             PARAMETERS, parameters, parameters_mut, _p::List<_p::Struct<node::Parameter>> = {
-                slot: 5, default: _p::eslpr()
+                slot: 5, default: None
             },
             IS_GENERIC, is_generic, is_generic_mut, bool = { slot: 288, default: false },
             NESTED_NODES, nested_nodes, nested_nodes_mut, _p::List<_p::Struct<node::NestedNode>> = {
-                slot: 1, default: _p::eslpr()
+                slot: 1, default: None
             },
             ANNOTATIONS, annotations, annotations_mut, _p::List<_p::Struct<Annotation>> = {
-                slot: 2, default: _p::eslpr()
+                slot: 2, default: None
             },
         },
         union {
@@ -48,7 +48,7 @@ _p::generate_file! {
                     DISCRIMINANT_COUNT, discriminant_count, discriminant_count_mut, u16 = { slot: 15, default: 0 },
                     DISCRIMINANT_OFFSET, discriminant_offset, discriminant_offset_mut, u32 = { slot: 8, default: 0 },
                     FIELDS, fields, fields_mut, _p::List<_p::Struct<__file::Field>> = {
-                        slot: 3, default: _p::eslpr()
+                        slot: 3, default: None
                     },
                 },
             },
@@ -56,7 +56,7 @@ _p::generate_file! {
                 mod: r#enum,
                 fields: {
                     ENUMERANTS, enumerants, enumerants_mut, _p::List<_p::Struct<__file::Enumerant>> = {
-                        slot: 3, default: _p::eslpr()
+                        slot: 3, default: None
                     },
                 },
             },
@@ -64,24 +64,24 @@ _p::generate_file! {
                 mod: interface,
                 fields: {
                     METHODS, methods, methods_mut, _p::List<_p::Struct<__file::Method>> = {
-                        slot: 3, default: _p::eslpr()
+                        slot: 3, default: None
                     },
                     SUPERCLASSES, superclasses, superclasses_mut, _p::List<_p::Struct<__file::Superclass>> = {
-                        slot: 4, default: _p::eslpr()
+                        slot: 4, default: None
                     },
                 },
             },
             group Const {
                 mod: r#const,
                 fields: {
-                    TYPE, r#type, type_mut, _p::Struct<__file::Type> = { slot: 3, default: _p::StructReader::empty() },
-                    VALUE, value, value_mut, _p::Struct<__file::Value> = { slot: 4, default: _p::StructReader::empty() },
+                    TYPE, r#type, type_mut, _p::Struct<__file::Type> = { slot: 3, default: None },
+                    VALUE, value, value_mut, _p::Struct<__file::Value> = { slot: 4, default: None },
                 },
             },
             group Annotation {
                 mod: annotation,
                 fields: {
-                    TYPE, r#type, type_mut, _p::Struct<__file::Type> = { slot: 3, default: _p::StructReader::empty() },
+                    TYPE, r#type, type_mut, _p::Struct<__file::Type> = { slot: 3, default: None },
                     TARGETS_FILE, targets_file, targets_file_mut, bool = { slot: 112, default: false },
                     TARGETS_CONST, targets_const, targets_const_mut, bool = { slot: 113, default: false },
                     TARGETS_ENUM, targets_enum, targets_enum_mut, bool = { slot: 114, default: false },
@@ -100,14 +100,14 @@ _p::generate_file! {
                 mod: parameter,
                 size: { data: 0, ptrs: 1 },
                 fields: {
-                    NAME, name, name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+                    NAME, name, name_mut, _p::Text = { slot: 0, default: None },
                 },
             },
             struct NestedNode {
                 mod: nested_node,
                 size: { data: 0, ptrs: 1 },
                 fields: {
-                    NAME, name, name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+                    NAME, name, name_mut, _p::Text = { slot: 0, default: None },
                     ID, id, id_mut, u64 = { slot: 0, default: 0 },
                 },
             },
@@ -116,9 +116,9 @@ _p::generate_file! {
                 size: { data: 0, ptrs: 1 },
                 fields: {
                     ID, id, id_mut, u64 = { slot: 0, default: 0 },
-                    DOC_COMMENT, doc_comment, doc_comment_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+                    DOC_COMMENT, doc_comment, doc_comment_mut, _p::Text = { slot: 0, default: None },
                     MEMBERS, members, members_mut, _p::List<_p::Struct<source_info::Member>> = {
-                        slot: 1, default: _p::eslpr()
+                        slot: 1, default: None
                     },
                 },
                 nested: {
@@ -126,7 +126,7 @@ _p::generate_file! {
                         mod: member,
                         size: { data: 0, ptrs: 1 },
                         fields: {
-                            DOC_COMMENT, doc_comment, doc_comment_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+                            DOC_COMMENT, doc_comment, doc_comment_mut, _p::Text = { slot: 0, default: None },
                         },
                     }
                 },
@@ -137,10 +137,10 @@ _p::generate_file! {
         mod: field,
         size: { data: 3, ptrs: 4 },
         fields: {
-            NAME, name, name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+            NAME, name, name_mut, _p::Text = { slot: 0, default: None },
             CODE_ORDER, code_order, code_order_mut, u16 = { slot: 0, default: 0 },
             ANNOTATIONS, annotations, annotations_mut, _p::List<_p::Struct<Annotation>> = {
-                slot: 1, default: _p::eslpr()
+                slot: 1, default: None
             },
             DISCRIMINANT_VALUE, discriminant_value, discriminant_value_mut, u16 = { slot: 1, default: 65535 },
             ORDINAL, ordinal, ordinal_mut, _p::Group<field::Ordinal> = (),
@@ -157,8 +157,8 @@ _p::generate_file! {
                 mod: slot,
                 fields: {
                     OFFSET, offset, offset_mut, u32 = { slot: 1, default: 0 },
-                    TYPE, r#type, type_mut, _p::Struct<__file::Type> = { slot: 2, default: _p::StructReader::empty() },
-                    DEFAULT_VALUE, default_value, default_value_mut, _p::Struct<__file::Value> = { slot: 3, default: _p::StructReader::empty() },
+                    TYPE, r#type, type_mut, _p::Struct<__file::Type> = { slot: 2, default: None },
+                    DEFAULT_VALUE, default_value, default_value_mut, _p::Struct<__file::Value> = { slot: 3, default: None },
                     HAD_EXPLICIT_DEFAULT, had_explicit_default, had_explicit_default_mut, bool = { slot: 128, default: false },
                 },
             },
@@ -185,10 +185,10 @@ _p::generate_file! {
         mod: enumerant,
         size: { data: 1, ptrs: 2 },
         fields: {
-            NAME, name, name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+            NAME, name, name_mut, _p::Text = { slot: 0, default: None },
             CODE_ORDER, code_order, code_order_mut, u16 = { slot: 0, default: 0 },
             ANNOTATIONS, annotations, annotations_mut, _p::List<_p::Struct<Annotation>> = {
-                slot: 1, default: _p::eslpr()
+                slot: 1, default: None
             },
         },
     },
@@ -198,7 +198,7 @@ _p::generate_file! {
         fields: {
             ID, id, id_mut, u64 = { slot: 0, default: 0 },
             BRAND, brand, brand_mut, _p::List<_p::Struct<Brand>> = {
-                slot: 0, default: _p::eslpr()
+                slot: 0, default: None
             }
         },
     },
@@ -206,17 +206,17 @@ _p::generate_file! {
         mod: method,
         size: { data: 3, ptrs: 5 },
         fields: {
-            NAME, name, name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+            NAME, name, name_mut, _p::Text = { slot: 0, default: None },
             CODE_ORDER, code_order, code_order_mut, u16 = { slot: 0, default: 0 },
             IMPLICIT_PARAMETERS, implicit_parameters, implicit_parameters_mut, _p::List<_p::Struct<node::Parameter>> = {
-                slot: 4, default: _p::eslpr()
+                slot: 4, default: None
             },
             PARAM_STRUCT_TYPE, param_struct_type, param_struct_type_mut, u64 = { slot: 1, default: 0 },
-            PARAM_BRAND, param_brand, param_brand_mut, _p::Struct<Brand> = { slot: 2, default: _p::StructReader::empty() },
+            PARAM_BRAND, param_brand, param_brand_mut, _p::Struct<Brand> = { slot: 2, default: None },
             RESULT_STRUCT_TYPE, result_struct_type, result_struct_type_mut, u64 = { slot: 2, default: 0 },
-            RESULT_BRAND, result_brand, result_brand_mut, _p::Struct<Brand> = { slot: 3, default: _p::StructReader::empty() },
+            RESULT_BRAND, result_brand, result_brand_mut, _p::Struct<Brand> = { slot: 3, default: None },
             ANNOTATIONS, annotations, annotations_mut, _p::List<_p::Struct<Annotation>> = {
-                slot: 1, default: _p::eslpr()
+                slot: 1, default: None
             },
         },
     },
@@ -252,28 +252,28 @@ _p::generate_file! {
             group List {
                 mod: list,
                 fields: {
-                    ELEMENT_TYPE, element_type, element_type_mut, _p::Struct<__file::Type> = { slot: 0, default: _p::StructReader::empty() },
+                    ELEMENT_TYPE, element_type, element_type_mut, _p::Struct<__file::Type> = { slot: 0, default: None },
                 },
             },
             group Enum {
                 mod: r#enum,
                 fields: {
                     TYPE_ID, type_id, type_id_mut, u64 = { slot: 1, default: 0 },
-                    BRAND, brand, brand_mut, _p::Struct<__file::Brand> = { slot: 0, default: _p::StructReader::empty() },
+                    BRAND, brand, brand_mut, _p::Struct<__file::Brand> = { slot: 0, default: None },
                 },
             },
             group Struct {
                 mod: r#struct,
                 fields: {
                     TYPE_ID, type_id, type_id_mut, u64 = { slot: 1, default: 0 },
-                    BRAND, brand, brand_mut, _p::Struct<__file::Brand> = { slot: 0, default: _p::StructReader::empty() },
+                    BRAND, brand, brand_mut, _p::Struct<__file::Brand> = { slot: 0, default: None },
                 },
             },
             group Interface {
                 mod: interface,
                 fields: {
                     TYPE_ID, type_id, type_id_mut, u64 = { slot: 1, default: 0 },
-                    BRAND, brand, brand_mut, _p::Struct<__file::Brand> = { slot: 0, default: _p::StructReader::empty() },
+                    BRAND, brand, brand_mut, _p::Struct<__file::Brand> = { slot: 0, default: None },
                 },
             },
             group AnyPointer {
@@ -323,7 +323,7 @@ _p::generate_file! {
         size: { data: 0, ptrs: 1 },
         fields: {
             SCOPES, scopes, scopes_mut, _p::List<_p::Struct<__file::brand::Scope>> = {
-                slot: 0, default: _p::eslpr()
+                slot: 0, default: None
             }
         },
         nested: {
@@ -337,7 +337,7 @@ _p::generate_file! {
                     tag_slot: 4,
                     fields: {
                         BIND, Bind, bind, bind_mut, _p::List<_p::Struct<__file::brand::Binding>> = {
-                            case: 0, slot: 0, default: _p::eslpr()
+                            case: 0, slot: 0, default: None
                         },
                         INHERIT, Inherit, inherit, inherit_mut, () = { case: 1 },
                     },
@@ -351,7 +351,7 @@ _p::generate_file! {
                     tag_slot: 0,
                     fields: {
                         UNBOUND, Unbound, unbound, unbound_mut, () = { case: 0 },
-                        TYPE, Type, r#type, type_mut, _p::Struct<__file::Type> = { case: 1, slot: 0, default: _p::StructReader::empty() },
+                        TYPE, Type, r#type, type_mut, _p::Struct<__file::Type> = { case: 1, slot: 0, default: None },
                     },
                 },
             },
@@ -376,13 +376,13 @@ _p::generate_file! {
                 UINT64, Uint64, uint64, uint64_mut, u64 = { case: 9, slot: 1, default: 0 },
                 FLOAT32, Float32, float32, float32_mut, f32 = { case: 10, slot: 1, default: 0. },
                 FLOAT64, Float64, float64, float64_mut, f64 = { case: 11, slot: 1, default: 0. },
-                TEXT, Text, text, text_mut, _p::Text = { case: 12, slot: 0, default: _p::text::Reader::empty() },
-                DATA, Data, data, data_mut, _p::Data = { case: 13, slot: 0, default: _p::data::Reader::empty() },
-                LIST, List, list, list_mut, _p::AnyPtr = { case: 14, slot: 0, default: _p::any::ptr::PtrReader::null() },
+                TEXT, Text, text, text_mut, _p::Text = { case: 12, slot: 0, default: None },
+                DATA, Data, data, data_mut, _p::Data = { case: 13, slot: 0, default: None },
+                LIST, List, list, list_mut, _p::AnyPtr = { case: 14, slot: 0, default: None },
                 ENUM, Enum, r#enum, enum_mut, u16 = { case: 15, slot: 1, default: 0 },
-                STRUCT, Struct, r#struct, struct_mut, _p::AnyPtr = { case: 16, slot: 0, default: _p::any::ptr::PtrReader::null() },
+                STRUCT, Struct, r#struct, struct_mut, _p::AnyPtr = { case: 16, slot: 0, default: None },
                 INTERFACE, Interface, interface, interface_mut, () = { case: 17 },
-                ANY_POINTER, AnyPointer, any_pointer, any_pointer_mut, _p::AnyPtr = { case: 18, slot: 0, default: _p::any::ptr::PtrReader::null() },
+                ANY_POINTER, AnyPointer, any_pointer, any_pointer_mut, _p::AnyPtr = { case: 18, slot: 0, default: None },
             },
         },
     },
@@ -392,9 +392,9 @@ _p::generate_file! {
         fields: {
             ID, id, id_mut, u64 = { slot: 0, default: 0 },
             BRAND, brand, brand_mut, _p::List<_p::Struct<Brand>> = {
-                slot: 1, default: _p::eslpr()
+                slot: 1, default: None
             },
-            VALUE, value, value_mut, _p::Struct<__file::Value> = { slot: 0, default: _p::StructReader::empty() },
+            VALUE, value, value_mut, _p::Struct<__file::Value> = { slot: 0, default: None },
         },
     },
     struct CapnpVersion {
@@ -410,15 +410,15 @@ _p::generate_file! {
         mod: code_generator_request,
         size: { data: 0, ptrs: 4 },
         fields: {
-            CAPNP_VERSION, capnp_version, capnp_version_mut, _p::Struct<CapnpVersion> = { slot: 2, default: _p::StructReader::empty() },
+            CAPNP_VERSION, capnp_version, capnp_version_mut, _p::Struct<CapnpVersion> = { slot: 2, default: None },
             NODES, nodes, nodes_mut, _p::List<_p::Struct<Node>> = {
-                slot: 0, default: _p::eslpr()
+                slot: 0, default: None
             },
             SOURCE_INFO, source_info, source_info_mut, _p::List<_p::Struct<node::SourceInfo>> = {
-                slot: 3, default: _p::eslpr()
+                slot: 3, default: None
             },
             REQUESTED_FILES, requested_files, requested_files_mut, _p::List<_p::Struct<code_generator_request::RequestedFile>> = {
-                slot: 1, default: _p::eslpr()
+                slot: 1, default: None
             }
         },
         nested: {
@@ -427,9 +427,9 @@ _p::generate_file! {
                 size: { data: 1, ptrs: 2 },
                 fields: {
                     ID, id, id_mut, u64 = { slot: 0, default: 0 },
-                    FILENAME, filename, filename_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+                    FILENAME, filename, filename_mut, _p::Text = { slot: 0, default: None },
                     IMPORTS, imports, imports_mut, _p::List<_p::Struct<__file::code_generator_request::requested_file::Import>> = {
-                        slot: 1, default: _p::eslpr()
+                        slot: 1, default: None
                     },
                 },
                 nested: {
@@ -438,7 +438,7 @@ _p::generate_file! {
                         size: { data: 1, ptrs: 1 },
                         fields: {
                             ID, id, id_mut, u64 = { slot: 0, default: 0 },
-                            NAME, name, name_mut, _p::Text = { slot: 0, default: _p::text::Reader::empty() },
+                            NAME, name, name_mut, _p::Text = { slot: 0, default: None },
                         },
                     },
                 },
diff --git a/recapnc/src/generator.rs b/recapnc/src/generator.rs
index a4dc562..d272d72 100644
--- a/recapnc/src/generator.rs
+++ b/recapnc/src/generator.rs
@@ -590,7 +590,7 @@ impl<'a> GeneratorContext<'a> {
 
                         quote!(_p::text::Reader::from_slice(#bytes))
                     }
-                    _ => quote!(_p::text::Reader::empty()),
+                    _ => quote!(None),
                 }
             }
             TypeKind::Data(()) => {
@@ -603,7 +603,7 @@ impl<'a> GeneratorContext<'a> {
 
                         quote!(_p::data::Reader::from_slice(#bytes))
                     }
-                    _ => quote!(_p::data::Reader::empty()),
+                    _ => quote!(None),
                 }
             }
             TypeKind::List(list) => {
@@ -625,7 +625,7 @@ impl<'a> GeneratorContext<'a> {
 
                         quote!(_p::ListReader::slice_unchecked(#words, #len, #element_size_quote))
                     }
-                    _ => quote!(_p::ListReader::empty(#element_size_quote)),
+                    _ => quote!(None),
                 }
             }
             TypeKind::Enum(info) => {
@@ -656,12 +656,10 @@ impl<'a> GeneratorContext<'a> {
 
                         quote!(_p::StructReader::slice_unchecked(#words, #size))
                     }
-                    _ => quote!(_p::StructReader::empty()),
+                    _ => quote!(None),
                 }
             }
-            TypeKind::Interface(_) => {
-                unimplemented!("cannot generate values for Capability fields")
-            }
+            TypeKind::Interface(_) => quote!(None),
             TypeKind::AnyPointer(kind) => {
                 let ptr = value.and_then(|v| v.any_pointer().field())
                     .map(|p| p.ptr()).filter(|p| !p.is_null());
@@ -673,7 +671,7 @@ impl<'a> GeneratorContext<'a> {
 
                             quote!(_p::PtrReader::slice_unchecked(#words))
                         } else {
-                            quote!(_p::PtrReader::null())
+                            quote!(None)
                         }
                         ConstraintKind::Struct(_) => if let Some(ptr) = ptr {
                             let reader = ptr.try_read_as::<AnyStruct>()
@@ -685,7 +683,7 @@ impl<'a> GeneratorContext<'a> {
 
                             quote!(_p::StructReader::slice_unchecked(#words, #size))
                         } else {
-                            quote!(_p::StructReader::empty())
+                            quote!(None)
                         }
                         ConstraintKind::List(_) => if let Some(ptr) = ptr {
                             let reader = ptr.try_read_as::<AnyList>()
@@ -697,9 +695,9 @@ impl<'a> GeneratorContext<'a> {
 
                             quote!(_p::ListReader::slice_unchecked(#words, #len, #size_quote))
                         } else {
-                            quote!(_p::ListReader::empty())
+                            quote!(None)
                         }
-                        ConstraintKind::Capability(_) => quote!(()),
+                        ConstraintKind::Capability(_) => quote!(None),
                     },
                     AnyPtrKind::Parameter(_) => todo!("generate default values for generic types"),
                     _ => unreachable!(),
diff --git a/tests/src/gen/capnp/test-import.capnp.rs b/tests/src/gen/capnp/test-import.capnp.rs
index 6ae1440..1b8ae77 100644
--- a/tests/src/gen/capnp/test-import.capnp.rs
+++ b/tests/src/gen/capnp/test-import.capnp.rs
@@ -100,7 +100,7 @@ impl TestImport {
         _p::Struct<__imports::capnp_test_capnp::TestAllTypes>,
     > {
         slot: 0u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> test_import::Reader<'p, T> {
diff --git a/tests/src/gen/capnp/test-import2.capnp.rs b/tests/src/gen/capnp/test-import2.capnp.rs
index 397df2c..a6321ed 100644
--- a/tests/src/gen/capnp/test-import2.capnp.rs
+++ b/tests/src/gen/capnp/test-import2.capnp.rs
@@ -100,13 +100,13 @@ impl TestImport2 {
         _p::Struct<__imports::capnp_test_capnp::TestAllTypes>,
     > {
         slot: 0u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const BAR: _p::Descriptor<
         _p::Struct<__imports::capnp_test_import_capnp::TestImport>,
     > = _p::Descriptor::<_p::Struct<__imports::capnp_test_import_capnp::TestImport>> {
         slot: 1u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> test_import2::Reader<'p, T> {
diff --git a/tests/src/gen/capnp/test.capnp.rs b/tests/src/gen/capnp/test.capnp.rs
index ac2da83..142b582 100644
--- a/tests/src/gen/capnp/test.capnp.rs
+++ b/tests/src/gen/capnp/test.capnp.rs
@@ -179,17 +179,17 @@ impl TestAllTypes {
     };
     const TEXT_FIELD: _p::Descriptor<_p::Text> = _p::Descriptor::<_p::Text> {
         slot: 0u32,
-        default: _p::text::Reader::empty(),
+        default: None,
     };
     const DATA_FIELD: _p::Descriptor<_p::Data> = _p::Descriptor::<_p::Data> {
         slot: 1u32,
-        default: _p::data::Reader::empty(),
+        default: None,
     };
     const STRUCT_FIELD: _p::Descriptor<_p::Struct<TestAllTypes>> = _p::Descriptor::<
         _p::Struct<TestAllTypes>,
     > {
         slot: 2u32,
-        default: _p::StructReader::empty(),
+        default: None,
     };
     const ENUM_FIELD: _p::Descriptor<_p::Enum<TestEnum>> = _p::Descriptor::<
         _p::Enum<TestEnum>,
@@ -200,81 +200,79 @@ impl TestAllTypes {
     const INTERFACE_FIELD: _p::Descriptor<()> = ();
     const VOID_LIST: _p::Descriptor<_p::List<()>> = _p::Descriptor::<_p::List<()>> {
         slot: 3u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<()>()),
+        default: None,
     };
     const BOOL_LIST: _p::Descriptor<_p::List<bool>> = _p::Descriptor::<_p::List<bool>> {
         slot: 4u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<bool>()),
+        default: None,
     };
     const INT8_LIST: _p::Descriptor<_p::List<i8>> = _p::Descriptor::<_p::List<i8>> {
         slot: 5u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<i8>()),
+        default: None,
     };
     const INT16_LIST: _p::Descriptor<_p::List<i16>> = _p::Descriptor::<_p::List<i16>> {
         slot: 6u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<i16>()),
+        default: None,
     };
     const INT32_LIST: _p::Descriptor<_p::List<i32>> = _p::Descriptor::<_p::List<i32>> {
         slot: 7u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<i32>()),
+        default: None,
     };
     const INT64_LIST: _p::Descriptor<_p::List<i64>> = _p::Descriptor::<_p::List<i64>> {
         slot: 8u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<i64>()),
+        default: None,
     };
     const U_INT8_LIST: _p::Descriptor<_p::List<u8>> = _p::Descriptor::<_p::List<u8>> {
         slot: 9u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<u8>()),
+        default: None,
     };
     const U_INT16_LIST: _p::Descriptor<_p::List<u16>> = _p::Descriptor::<_p::List<u16>> {
         slot: 10u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<u16>()),
+        default: None,
     };
     const U_INT32_LIST: _p::Descriptor<_p::List<u32>> = _p::Descriptor::<_p::List<u32>> {
         slot: 11u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<u32>()),
+        default: None,
     };
     const U_INT64_LIST: _p::Descriptor<_p::List<u64>> = _p::Descriptor::<_p::List<u64>> {
         slot: 12u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<u64>()),
+        default: None,
     };
     const FLOAT32_LIST: _p::Descriptor<_p::List<f32>> = _p::Descriptor::<_p::List<f32>> {
         slot: 13u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<f32>()),
+        default: None,
     };
     const FLOAT64_LIST: _p::Descriptor<_p::List<f64>> = _p::Descriptor::<_p::List<f64>> {
         slot: 14u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<f64>()),
+        default: None,
     };
     const TEXT_LIST: _p::Descriptor<_p::List<_p::Text>> = _p::Descriptor::<
         _p::List<_p::Text>,
     > {
         slot: 15u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<_p::Text>()),
+        default: None,
     };
     const DATA_LIST: _p::Descriptor<_p::List<_p::Data>> = _p::Descriptor::<
         _p::List<_p::Data>,
     > {
         slot: 16u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<_p::Data>()),
+        default: None,
     };
     const STRUCT_LIST: _p::Descriptor<_p::List<_p::Struct<TestAllTypes>>> = _p::Descriptor::<
         _p::List<_p::Struct<TestAllTypes>>,
     > {
         slot: 17u32,
-        default: _p::ListReader::empty(
-            _p::ElementSize::size_of::<_p::Struct<TestAllTypes>>(),
-        ),
+        default: None,
     };
     const ENUM_LIST: _p::Descriptor<_p::List<_p::Enum<TestEnum>>> = _p::Descriptor::<
         _p::List<_p::Enum<TestEnum>>,
     > {
         slot: 18u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<_p::Enum<TestEnum>>()),
+        default: None,
     };
     const INTERFACE_LIST: _p::Descriptor<_p::List<()>> = _p::Descriptor::<_p::List<()>> {
         slot: 19u32,
-        default: _p::ListReader::empty(_p::ElementSize::size_of::<()>()),
+        default: None,
     };
 }
 impl<'p, T: _p::rpc::Table + 'p> test_all_types::Reader<'p, T> {