diff --git a/gen/proto/go/coroutine/v1/coroutine.pb.go b/gen/proto/go/coroutine/v1/coroutine.pb.go
index 561aec0..5046d97 100644
--- a/gen/proto/go/coroutine/v1/coroutine.pb.go
+++ b/gen/proto/go/coroutine/v1/coroutine.pb.go
@@ -26,9 +26,17 @@ type State struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	Build *Build  `protobuf:"bytes,1,opt,name=build,proto3" json:"build,omitempty"`
-	State []byte  `protobuf:"bytes,2,opt,name=state,proto3" json:"state,omitempty"`
+	// Build is information about the build in which the coruotine state
+	// was generated.
+	Build *Build `protobuf:"bytes,1,opt,name=build,proto3" json:"build,omitempty"`
+	// State is a serialized representation of the objects in the program
+	// that are reachable from the coroutine stack.
+	State []byte `protobuf:"bytes,2,opt,name=state,proto3" json:"state,omitempty"`
+	// Types is the set of types used by the object graph.
 	Types []*Type `protobuf:"bytes,3,rep,name=types,proto3" json:"types,omitempty"`
+	// Functions is the set of functions, methods and closures referenced
+	// by the object graph.
+	Functions []*Function `protobuf:"bytes,4,rep,name=functions,proto3" json:"functions,omitempty"`
 }
 
 func (x *State) Reset() {
@@ -84,6 +92,13 @@ func (x *State) GetTypes() []*Type {
 	return nil
 }
 
+func (x *State) GetFunctions() []*Function {
+	if x != nil {
+		return x.Functions
+	}
+	return nil
+}
+
 // Build is info about the build in which a durable coroutine
 // is/was running.
 type Build struct {
@@ -154,32 +169,38 @@ var File_coroutine_v1_coroutine_proto protoreflect.FileDescriptor
 var file_coroutine_v1_coroutine_proto_rawDesc = []byte{
 	0x0a, 0x1c, 0x63, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2f, 0x76, 0x31, 0x2f, 0x63,
 	0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x0c,
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+	0x58, 0xaa, 0x02, 0x0c, 0x43, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2e, 0x56, 0x31,
+	0xca, 0x02, 0x0c, 0x43, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x5c, 0x56, 0x31, 0xe2,
+	0x02, 0x18, 0x43, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x5c, 0x56, 0x31, 0x5c, 0x47,
+	0x50, 0x42, 0x4d, 0x65, 0x74, 0x61, 0x64, 0x61, 0x74, 0x61, 0xea, 0x02, 0x0d, 0x43, 0x6f, 0x72,
+	0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x3a, 0x3a, 0x56, 0x31, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74,
+	0x6f, 0x33,
 }
 
 var (
@@ -196,18 +217,20 @@ func file_coroutine_v1_coroutine_proto_rawDescGZIP() []byte {
 
 var file_coroutine_v1_coroutine_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
 var file_coroutine_v1_coroutine_proto_goTypes = []interface{}{
-	(*State)(nil), // 0: coroutine.v1.State
-	(*Build)(nil), // 1: coroutine.v1.Build
-	(*Type)(nil),  // 2: coroutine.v1.Type
+	(*State)(nil),    // 0: coroutine.v1.State
+	(*Build)(nil),    // 1: coroutine.v1.Build
+	(*Type)(nil),     // 2: coroutine.v1.Type
+	(*Function)(nil), // 3: coroutine.v1.Function
 }
 var file_coroutine_v1_coroutine_proto_depIdxs = []int32{
 	1, // 0: coroutine.v1.State.build:type_name -> coroutine.v1.Build
 	2, // 1: coroutine.v1.State.types:type_name -> coroutine.v1.Type
-	2, // [2:2] is the sub-list for method output_type
-	2, // [2:2] is the sub-list for method input_type
-	2, // [2:2] is the sub-list for extension type_name
-	2, // [2:2] is the sub-list for extension extendee
-	0, // [0:2] is the sub-list for field type_name
+	3, // 2: coroutine.v1.State.functions:type_name -> coroutine.v1.Function
+	3, // [3:3] is the sub-list for method output_type
+	3, // [3:3] is the sub-list for method input_type
+	3, // [3:3] is the sub-list for extension type_name
+	3, // [3:3] is the sub-list for extension extendee
+	0, // [0:3] is the sub-list for field type_name
 }
 
 func init() { file_coroutine_v1_coroutine_proto_init() }
@@ -215,6 +238,7 @@ func file_coroutine_v1_coroutine_proto_init() {
 	if File_coroutine_v1_coroutine_proto != nil {
 		return
 	}
+	file_coroutine_v1_function_proto_init()
 	file_coroutine_v1_type_proto_init()
 	if !protoimpl.UnsafeEnabled {
 		file_coroutine_v1_coroutine_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
diff --git a/gen/proto/go/coroutine/v1/coroutine_vtproto.pb.go b/gen/proto/go/coroutine/v1/coroutine_vtproto.pb.go
index 5c102b4..985cb08 100644
--- a/gen/proto/go/coroutine/v1/coroutine_vtproto.pb.go
+++ b/gen/proto/go/coroutine/v1/coroutine_vtproto.pb.go
@@ -47,6 +47,18 @@ func (m *State) MarshalToSizedBufferVT(dAtA []byte) (int, error) {
 		i -= len(m.unknownFields)
 		copy(dAtA[i:], m.unknownFields)
 	}
+	if len(m.Functions) > 0 {
+		for iNdEx := len(m.Functions) - 1; iNdEx >= 0; iNdEx-- {
+			size, err := m.Functions[iNdEx].MarshalToSizedBufferVT(dAtA[:i])
+			if err != nil {
+				return 0, err
+			}
+			i -= size
+			i = encodeVarint(dAtA, i, uint64(size))
+			i--
+			dAtA[i] = 0x22
+		}
+	}
 	if len(m.Types) > 0 {
 		for iNdEx := len(m.Types) - 1; iNdEx >= 0; iNdEx-- {
 			size, err := m.Types[iNdEx].MarshalToSizedBufferVT(dAtA[:i])
@@ -153,6 +165,12 @@ func (m *State) SizeVT() (n int) {
 			n += 1 + l + sov(uint64(l))
 		}
 	}
+	if len(m.Functions) > 0 {
+		for _, e := range m.Functions {
+			l = e.SizeVT()
+			n += 1 + l + sov(uint64(l))
+		}
+	}
 	n += len(m.unknownFields)
 	return n
 }
@@ -312,6 +330,40 @@ func (m *State) UnmarshalVT(dAtA []byte) error {
 				return err
 			}
 			iNdEx = postIndex
+		case 4:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Functions", wireType)
+			}
+			var msglen int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				msglen |= int(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if msglen < 0 {
+				return ErrInvalidLength
+			}
+			postIndex := iNdEx + msglen
+			if postIndex < 0 {
+				return ErrInvalidLength
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Functions = append(m.Functions, &Function{})
+			if err := m.Functions[len(m.Functions)-1].UnmarshalVT(dAtA[iNdEx:postIndex]); err != nil {
+				return err
+			}
+			iNdEx = postIndex
 		default:
 			iNdEx = preIndex
 			skippy, err := skip(dAtA[iNdEx:])
diff --git a/gen/proto/go/coroutine/v1/function.pb.go b/gen/proto/go/coroutine/v1/function.pb.go
new file mode 100644
index 0000000..a070939
--- /dev/null
+++ b/gen/proto/go/coroutine/v1/function.pb.go
@@ -0,0 +1,177 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.31.0
+// 	protoc        (unknown)
+// source: coroutine/v1/function.proto
+
+package coroutinev1
+
+import (
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+// Function represents a function, method or closure in the program.
+type Function struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// Name is the name of the function.
+	Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
+	// Type is an identifier for the function's type.
+	Type int32 `protobuf:"varint,2,opt,name=type,proto3" json:"type,omitempty"`
+	// Closure is an identifier for a struct type that represents the
+	// memory layout of the closure.
+	Closure int32 `protobuf:"varint,3,opt,name=closure,proto3" json:"closure,omitempty"`
+}
+
+func (x *Function) Reset() {
+	*x = Function{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_coroutine_v1_function_proto_msgTypes[0]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *Function) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*Function) ProtoMessage() {}
+
+func (x *Function) ProtoReflect() protoreflect.Message {
+	mi := &file_coroutine_v1_function_proto_msgTypes[0]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use Function.ProtoReflect.Descriptor instead.
+func (*Function) Descriptor() ([]byte, []int) {
+	return file_coroutine_v1_function_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *Function) GetName() string {
+	if x != nil {
+		return x.Name
+	}
+	return ""
+}
+
+func (x *Function) GetType() int32 {
+	if x != nil {
+		return x.Type
+	}
+	return 0
+}
+
+func (x *Function) GetClosure() int32 {
+	if x != nil {
+		return x.Closure
+	}
+	return 0
+}
+
+var File_coroutine_v1_function_proto protoreflect.FileDescriptor
+
+var file_coroutine_v1_function_proto_rawDesc = []byte{
+	0x0a, 0x1b, 0x63, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2f, 0x76, 0x31, 0x2f, 0x66,
+	0x75, 0x6e, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x0c, 0x63,
+	0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2e, 0x76, 0x31, 0x22, 0x4c, 0x0a, 0x08, 0x46,
+	0x75, 0x6e, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x12, 0x12, 0x0a, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x18,
+	0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x04, 0x6e, 0x61, 0x6d, 0x65, 0x12, 0x12, 0x0a, 0x04, 0x74,
+	0x79, 0x70, 0x65, 0x18, 0x02, 0x20, 0x01, 0x28, 0x05, 0x52, 0x04, 0x74, 0x79, 0x70, 0x65, 0x12,
+	0x18, 0x0a, 0x07, 0x63, 0x6c, 0x6f, 0x73, 0x75, 0x72, 0x65, 0x18, 0x03, 0x20, 0x01, 0x28, 0x05,
+	0x52, 0x07, 0x63, 0x6c, 0x6f, 0x73, 0x75, 0x72, 0x65, 0x42, 0xbc, 0x01, 0x0a, 0x10, 0x63, 0x6f,
+	0x6d, 0x2e, 0x63, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2e, 0x76, 0x31, 0x42, 0x0d,
+	0x46, 0x75, 0x6e, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x50, 0x72, 0x6f, 0x74, 0x6f, 0x50, 0x01, 0x5a,
+	0x48, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62, 0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x73, 0x74, 0x65, 0x61,
+	0x6c, 0x74, 0x68, 0x72, 0x6f, 0x63, 0x6b, 0x65, 0x74, 0x2f, 0x63, 0x6f, 0x72, 0x6f, 0x75, 0x74,
+	0x69, 0x6e, 0x65, 0x2f, 0x67, 0x65, 0x6e, 0x2f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2f, 0x67, 0x6f,
+	0x2f, 0x63, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2f, 0x76, 0x31, 0x3b, 0x63, 0x6f,
+	0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x76, 0x31, 0xa2, 0x02, 0x03, 0x43, 0x58, 0x58, 0xaa,
+	0x02, 0x0c, 0x43, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x2e, 0x56, 0x31, 0xca, 0x02,
+	0x0c, 0x43, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x5c, 0x56, 0x31, 0xe2, 0x02, 0x18,
+	0x43, 0x6f, 0x72, 0x6f, 0x75, 0x74, 0x69, 0x6e, 0x65, 0x5c, 0x56, 0x31, 0x5c, 0x47, 0x50, 0x42,
+	0x4d, 0x65, 0x74, 0x61, 0x64, 0x61, 0x74, 0x61, 0xea, 0x02, 0x0d, 0x43, 0x6f, 0x72, 0x6f, 0x75,
+	0x74, 0x69, 0x6e, 0x65, 0x3a, 0x3a, 0x56, 0x31, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
+}
+
+var (
+	file_coroutine_v1_function_proto_rawDescOnce sync.Once
+	file_coroutine_v1_function_proto_rawDescData = file_coroutine_v1_function_proto_rawDesc
+)
+
+func file_coroutine_v1_function_proto_rawDescGZIP() []byte {
+	file_coroutine_v1_function_proto_rawDescOnce.Do(func() {
+		file_coroutine_v1_function_proto_rawDescData = protoimpl.X.CompressGZIP(file_coroutine_v1_function_proto_rawDescData)
+	})
+	return file_coroutine_v1_function_proto_rawDescData
+}
+
+var file_coroutine_v1_function_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_coroutine_v1_function_proto_goTypes = []interface{}{
+	(*Function)(nil), // 0: coroutine.v1.Function
+}
+var file_coroutine_v1_function_proto_depIdxs = []int32{
+	0, // [0:0] is the sub-list for method output_type
+	0, // [0:0] is the sub-list for method input_type
+	0, // [0:0] is the sub-list for extension type_name
+	0, // [0:0] is the sub-list for extension extendee
+	0, // [0:0] is the sub-list for field type_name
+}
+
+func init() { file_coroutine_v1_function_proto_init() }
+func file_coroutine_v1_function_proto_init() {
+	if File_coroutine_v1_function_proto != nil {
+		return
+	}
+	if !protoimpl.UnsafeEnabled {
+		file_coroutine_v1_function_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*Function); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: file_coroutine_v1_function_proto_rawDesc,
+			NumEnums:      0,
+			NumMessages:   1,
+			NumExtensions: 0,
+			NumServices:   0,
+		},
+		GoTypes:           file_coroutine_v1_function_proto_goTypes,
+		DependencyIndexes: file_coroutine_v1_function_proto_depIdxs,
+		MessageInfos:      file_coroutine_v1_function_proto_msgTypes,
+	}.Build()
+	File_coroutine_v1_function_proto = out.File
+	file_coroutine_v1_function_proto_rawDesc = nil
+	file_coroutine_v1_function_proto_goTypes = nil
+	file_coroutine_v1_function_proto_depIdxs = nil
+}
diff --git a/gen/proto/go/coroutine/v1/function_vtproto.pb.go b/gen/proto/go/coroutine/v1/function_vtproto.pb.go
new file mode 100644
index 0000000..74346ae
--- /dev/null
+++ b/gen/proto/go/coroutine/v1/function_vtproto.pb.go
@@ -0,0 +1,313 @@
+// Code generated by protoc-gen-go-vtproto. DO NOT EDIT.
+// protoc-gen-go-vtproto version: v0.5.0
+// source: coroutine/v1/function.proto
+
+package coroutinev1
+
+import (
+	fmt "fmt"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	io "io"
+	bits "math/bits"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+func (m *Function) MarshalVT() (dAtA []byte, err error) {
+	if m == nil {
+		return nil, nil
+	}
+	size := m.SizeVT()
+	dAtA = make([]byte, size)
+	n, err := m.MarshalToSizedBufferVT(dAtA[:size])
+	if err != nil {
+		return nil, err
+	}
+	return dAtA[:n], nil
+}
+
+func (m *Function) MarshalToVT(dAtA []byte) (int, error) {
+	size := m.SizeVT()
+	return m.MarshalToSizedBufferVT(dAtA[:size])
+}
+
+func (m *Function) MarshalToSizedBufferVT(dAtA []byte) (int, error) {
+	if m == nil {
+		return 0, nil
+	}
+	i := len(dAtA)
+	_ = i
+	var l int
+	_ = l
+	if m.unknownFields != nil {
+		i -= len(m.unknownFields)
+		copy(dAtA[i:], m.unknownFields)
+	}
+	if m.Closure != 0 {
+		i = encodeVarint(dAtA, i, uint64(m.Closure))
+		i--
+		dAtA[i] = 0x18
+	}
+	if m.Type != 0 {
+		i = encodeVarint(dAtA, i, uint64(m.Type))
+		i--
+		dAtA[i] = 0x10
+	}
+	if len(m.Name) > 0 {
+		i -= len(m.Name)
+		copy(dAtA[i:], m.Name)
+		i = encodeVarint(dAtA, i, uint64(len(m.Name)))
+		i--
+		dAtA[i] = 0xa
+	}
+	return len(dAtA) - i, nil
+}
+
+func encodeVarint(dAtA []byte, offset int, v uint64) int {
+	offset -= sov(v)
+	base := offset
+	for v >= 1<<7 {
+		dAtA[offset] = uint8(v&0x7f | 0x80)
+		v >>= 7
+		offset++
+	}
+	dAtA[offset] = uint8(v)
+	return base
+}
+func (m *Function) SizeVT() (n int) {
+	if m == nil {
+		return 0
+	}
+	var l int
+	_ = l
+	l = len(m.Name)
+	if l > 0 {
+		n += 1 + l + sov(uint64(l))
+	}
+	if m.Type != 0 {
+		n += 1 + sov(uint64(m.Type))
+	}
+	if m.Closure != 0 {
+		n += 1 + sov(uint64(m.Closure))
+	}
+	n += len(m.unknownFields)
+	return n
+}
+
+func sov(x uint64) (n int) {
+	return (bits.Len64(x|1) + 6) / 7
+}
+func soz(x uint64) (n int) {
+	return sov(uint64((x << 1) ^ uint64((int64(x) >> 63))))
+}
+func (m *Function) UnmarshalVT(dAtA []byte) error {
+	l := len(dAtA)
+	iNdEx := 0
+	for iNdEx < l {
+		preIndex := iNdEx
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return ErrIntOverflow
+			}
+			if iNdEx >= l {
+				return io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= uint64(b&0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		fieldNum := int32(wire >> 3)
+		wireType := int(wire & 0x7)
+		if wireType == 4 {
+			return fmt.Errorf("proto: Function: wiretype end group for non-group")
+		}
+		if fieldNum <= 0 {
+			return fmt.Errorf("proto: Function: illegal tag %d (wire type %d)", fieldNum, wire)
+		}
+		switch fieldNum {
+		case 1:
+			if wireType != 2 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Name", wireType)
+			}
+			var stringLen uint64
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				stringLen |= uint64(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			intStringLen := int(stringLen)
+			if intStringLen < 0 {
+				return ErrInvalidLength
+			}
+			postIndex := iNdEx + intStringLen
+			if postIndex < 0 {
+				return ErrInvalidLength
+			}
+			if postIndex > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.Name = string(dAtA[iNdEx:postIndex])
+			iNdEx = postIndex
+		case 2:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Type", wireType)
+			}
+			m.Type = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Type |= int32(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		case 3:
+			if wireType != 0 {
+				return fmt.Errorf("proto: wrong wireType = %d for field Closure", wireType)
+			}
+			m.Closure = 0
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				m.Closure |= int32(b&0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+		default:
+			iNdEx = preIndex
+			skippy, err := skip(dAtA[iNdEx:])
+			if err != nil {
+				return err
+			}
+			if (skippy < 0) || (iNdEx+skippy) < 0 {
+				return ErrInvalidLength
+			}
+			if (iNdEx + skippy) > l {
+				return io.ErrUnexpectedEOF
+			}
+			m.unknownFields = append(m.unknownFields, dAtA[iNdEx:iNdEx+skippy]...)
+			iNdEx += skippy
+		}
+	}
+
+	if iNdEx > l {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+
+func skip(dAtA []byte) (n int, err error) {
+	l := len(dAtA)
+	iNdEx := 0
+	depth := 0
+	for iNdEx < l {
+		var wire uint64
+		for shift := uint(0); ; shift += 7 {
+			if shift >= 64 {
+				return 0, ErrIntOverflow
+			}
+			if iNdEx >= l {
+				return 0, io.ErrUnexpectedEOF
+			}
+			b := dAtA[iNdEx]
+			iNdEx++
+			wire |= (uint64(b) & 0x7F) << shift
+			if b < 0x80 {
+				break
+			}
+		}
+		wireType := int(wire & 0x7)
+		switch wireType {
+		case 0:
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				iNdEx++
+				if dAtA[iNdEx-1] < 0x80 {
+					break
+				}
+			}
+		case 1:
+			iNdEx += 8
+		case 2:
+			var length int
+			for shift := uint(0); ; shift += 7 {
+				if shift >= 64 {
+					return 0, ErrIntOverflow
+				}
+				if iNdEx >= l {
+					return 0, io.ErrUnexpectedEOF
+				}
+				b := dAtA[iNdEx]
+				iNdEx++
+				length |= (int(b) & 0x7F) << shift
+				if b < 0x80 {
+					break
+				}
+			}
+			if length < 0 {
+				return 0, ErrInvalidLength
+			}
+			iNdEx += length
+		case 3:
+			depth++
+		case 4:
+			if depth == 0 {
+				return 0, ErrUnexpectedEndOfGroup
+			}
+			depth--
+		case 5:
+			iNdEx += 4
+		default:
+			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
+		}
+		if iNdEx < 0 {
+			return 0, ErrInvalidLength
+		}
+		if depth == 0 {
+			return iNdEx, nil
+		}
+	}
+	return 0, io.ErrUnexpectedEOF
+}
+
+var (
+	ErrInvalidLength        = fmt.Errorf("proto: negative length found during unmarshaling")
+	ErrIntOverflow          = fmt.Errorf("proto: integer overflow")
+	ErrUnexpectedEndOfGroup = fmt.Errorf("proto: unexpected end of group")
+)
diff --git a/gen/proto/go/coroutine/v1/type_vtproto.pb.go b/gen/proto/go/coroutine/v1/type_vtproto.pb.go
index 3e7de17..bdbb2d1 100644
--- a/gen/proto/go/coroutine/v1/type_vtproto.pb.go
+++ b/gen/proto/go/coroutine/v1/type_vtproto.pb.go
@@ -8,7 +8,6 @@ import (
 	fmt "fmt"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	io "io"
-	bits "math/bits"
 )
 
 const (
@@ -264,17 +263,6 @@ func (m *Field) MarshalToSizedBufferVT(dAtA []byte) (int, error) {
 	return len(dAtA) - i, nil
 }
 
-func encodeVarint(dAtA []byte, offset int, v uint64) int {
-	offset -= sov(v)
-	base := offset
-	for v >= 1<<7 {
-		dAtA[offset] = uint8(v&0x7f | 0x80)
-		v >>= 7
-		offset++
-	}
-	dAtA[offset] = uint8(v)
-	return base
-}
 func (m *Type) SizeVT() (n int) {
 	if m == nil {
 		return 0
@@ -375,12 +363,6 @@ func (m *Field) SizeVT() (n int) {
 	return n
 }
 
-func sov(x uint64) (n int) {
-	return (bits.Len64(x|1) + 6) / 7
-}
-func soz(x uint64) (n int) {
-	return sov(uint64((x << 1) ^ uint64((int64(x) >> 63))))
-}
 func (m *Type) UnmarshalVT(dAtA []byte) error {
 	l := len(dAtA)
 	iNdEx := 0
@@ -1117,88 +1099,3 @@ func (m *Field) UnmarshalVT(dAtA []byte) error {
 	}
 	return nil
 }
-
-func skip(dAtA []byte) (n int, err error) {
-	l := len(dAtA)
-	iNdEx := 0
-	depth := 0
-	for iNdEx < l {
-		var wire uint64
-		for shift := uint(0); ; shift += 7 {
-			if shift >= 64 {
-				return 0, ErrIntOverflow
-			}
-			if iNdEx >= l {
-				return 0, io.ErrUnexpectedEOF
-			}
-			b := dAtA[iNdEx]
-			iNdEx++
-			wire |= (uint64(b) & 0x7F) << shift
-			if b < 0x80 {
-				break
-			}
-		}
-		wireType := int(wire & 0x7)
-		switch wireType {
-		case 0:
-			for shift := uint(0); ; shift += 7 {
-				if shift >= 64 {
-					return 0, ErrIntOverflow
-				}
-				if iNdEx >= l {
-					return 0, io.ErrUnexpectedEOF
-				}
-				iNdEx++
-				if dAtA[iNdEx-1] < 0x80 {
-					break
-				}
-			}
-		case 1:
-			iNdEx += 8
-		case 2:
-			var length int
-			for shift := uint(0); ; shift += 7 {
-				if shift >= 64 {
-					return 0, ErrIntOverflow
-				}
-				if iNdEx >= l {
-					return 0, io.ErrUnexpectedEOF
-				}
-				b := dAtA[iNdEx]
-				iNdEx++
-				length |= (int(b) & 0x7F) << shift
-				if b < 0x80 {
-					break
-				}
-			}
-			if length < 0 {
-				return 0, ErrInvalidLength
-			}
-			iNdEx += length
-		case 3:
-			depth++
-		case 4:
-			if depth == 0 {
-				return 0, ErrUnexpectedEndOfGroup
-			}
-			depth--
-		case 5:
-			iNdEx += 4
-		default:
-			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
-		}
-		if iNdEx < 0 {
-			return 0, ErrInvalidLength
-		}
-		if depth == 0 {
-			return iNdEx, nil
-		}
-	}
-	return 0, io.ErrUnexpectedEOF
-}
-
-var (
-	ErrInvalidLength        = fmt.Errorf("proto: negative length found during unmarshaling")
-	ErrIntOverflow          = fmt.Errorf("proto: integer overflow")
-	ErrUnexpectedEndOfGroup = fmt.Errorf("proto: unexpected end of group")
-)
diff --git a/proto/coroutine/v1/coroutine.proto b/proto/coroutine/v1/coroutine.proto
index 5f8d1c8..d4d6cad 100644
--- a/proto/coroutine/v1/coroutine.proto
+++ b/proto/coroutine/v1/coroutine.proto
@@ -2,13 +2,25 @@ syntax = "proto3";
 
 package coroutine.v1;
 
+import "coroutine/v1/function.proto";
 import "coroutine/v1/type.proto";
 
 // State is durable coroutine state.
 message State {
+  // Build is information about the build in which the coruotine state
+  // was generated.
   Build build = 1;
+
+  // State is a serialized representation of the objects in the program
+  // that are reachable from the coroutine stack.
   bytes state = 2;
+
+  // Types is the set of types used by the object graph.
   repeated Type types = 3;
+
+  // Functions is the set of functions, methods and closures referenced
+  // by the object graph.
+  repeated Function functions = 4;
 }
 
 // Build is info about the build in which a durable coroutine
diff --git a/proto/coroutine/v1/function.proto b/proto/coroutine/v1/function.proto
new file mode 100644
index 0000000..4b6aba7
--- /dev/null
+++ b/proto/coroutine/v1/function.proto
@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package coroutine.v1;
+
+// Function represents a function, method or closure in the program.
+message Function {
+  // Name is the name of the function.
+  string name = 1;
+
+  // Type is an identifier for the function's type.
+  int32 type = 2;
+
+  // Closure is an identifier for a struct type that represents the
+  // memory layout of the closure.
+  int32 closure = 3;
+}
diff --git a/types/reflect.go b/types/reflect.go
index f178193..58ebde3 100644
--- a/types/reflect.go
+++ b/types/reflect.go
@@ -610,51 +610,38 @@ func deserializeStructFields(d *Deserializer, p unsafe.Pointer, n int, field fun
 }
 
 func serializeFunc(s *Serializer, t reflect.Type, p unsafe.Pointer) {
-	// p is a pointer to a function value, function values are pointers to a
-	// memory location starting with the address of the function, hence the
-	// double indirection here.
-	p = *(*unsafe.Pointer)(p)
-	if p == nil { // nil function value
-		serializeBool(s, false)
+	fn := *(**function)(p)
+	if fn == nil {
+		// Function IDs start at 1; use 0 to represent nil ptr.
+		serializeVarint(s, 0)
 		return
 	}
-	serializeBool(s, true)
 
-	addr := *(*uintptr)(p)
-	fn := FuncByAddr(addr)
-	if fn == nil {
-		panic(fmt.Sprintf("function not found at address %v", addr))
-	}
-	serializeString(s, &fn.Name)
+	id, closure := s.funcs.RegisterAddr(fn.addr)
+	serializeVarint(s, int(id))
 
-	if fn.Closure != nil {
-		t := fn.Closure
-		serializeStructFields(s, p, t.NumField()-1, func(i int) reflect.StructField {
-			return t.Field(i + 1)
+	if closure != nil {
+		p = unsafe.Pointer(fn)
+		// Skip the first field, which is the function ptr.
+		serializeStructFields(s, p, closure.NumField()-1, func(i int) reflect.StructField {
+			return closure.Field(i + 1)
 		})
 	}
 }
 
 func deserializeFunc(d *Deserializer, t reflect.Type, p unsafe.Pointer) {
-	var ok bool
-	deserializeBool(d, &ok)
-	if !ok {
-		*(**Func)(p) = nil
+	id := deserializeVarint(d)
+	if id == 0 {
+		*(**function)(p) = nil
 		return
 	}
 
-	var name string
-	deserializeString(d, &name)
-
-	fn := FuncByName(name)
-	if fn == nil {
-		panic(name + ": function symbol not found in the program")
-	}
+	fn := d.funcs.ToFunc(funcid(id))
 	if fn.Type == nil {
-		panic(name + ": function type is missing")
+		panic(fn.Name + ": function type is missing")
 	}
 	if !t.AssignableTo(fn.Type) {
-		panic(name + ": function type mismatch: " + fn.Type.String() + " != " + t.String())
+		panic(fn.Name + ": function type mismatch: " + fn.Type.String() + " != " + t.String())
 	}
 
 	if fn.Closure != nil {
@@ -670,7 +657,10 @@ func deserializeFunc(d *Deserializer, t reflect.Type, p unsafe.Pointer) {
 
 		*(*unsafe.Pointer)(p) = closure
 	} else {
-		*(**Func)(p) = fn
+		// Avoid an allocation by storing a pointer to the immutable Func.
+		// This works because the addr is the first element in both the Func
+		// and function structs.
+		*(**function)(p) = (*function)(unsafe.Pointer(fn))
 	}
 }
 
diff --git a/types/serde.go b/types/serde.go
index 2a6d86f..e3adfdb 100644
--- a/types/serde.go
+++ b/types/serde.go
@@ -53,9 +53,10 @@ func Serialize(x any) ([]byte, error) {
 	serializeAny(s, t, p)
 
 	state := &coroutinev1.State{
-		State: s.b,
-		Build: buildInfo,
-		Types: s.types.types,
+		State:     s.b,
+		Build:     buildInfo,
+		Types:     s.types.types,
+		Functions: s.funcs.funcs,
 	}
 	return state.MarshalVT()
 }
@@ -70,7 +71,7 @@ func Deserialize(b []byte) (interface{}, error) {
 		return nil, fmt.Errorf("%w: got %v, expect %v", ErrBuildIDMismatch, state.Build.Id, buildInfo.Id)
 	}
 
-	d := newDeserializer(state.State, state.Types)
+	d := newDeserializer(state.State, state.Types, state.Functions)
 	var x interface{}
 	px := &x
 	t := reflect.TypeOf(px).Elem()
@@ -85,6 +86,7 @@ func Deserialize(b []byte) (interface{}, error) {
 type Deserializer struct {
 	serdes *serdemap
 	types  *typemap
+	funcs  *funcmap
 
 	// TODO: make it a slice since pointer ids is the sequence of integers
 	// starting at 1.
@@ -94,10 +96,12 @@ type Deserializer struct {
 	b []byte
 }
 
-func newDeserializer(b []byte, types []*coroutinev1.Type) *Deserializer {
+func newDeserializer(b []byte, ctypes []*coroutinev1.Type, cfuncs []*coroutinev1.Function) *Deserializer {
+	types := newTypeMap(serdes, ctypes)
 	return &Deserializer{
 		serdes: serdes,
-		types:  newTypeMap(serdes, types),
+		types:  types,
+		funcs:  newFuncMap(types, cfuncs),
 		ptrs:   make(map[sID]unsafe.Pointer),
 		b:      b,
 	}
@@ -156,6 +160,7 @@ func (d *Deserializer) store(i sID, p unsafe.Pointer) {
 type Serializer struct {
 	serdes     *serdemap
 	types      *typemap
+	funcs      *funcmap
 	ptrs       map[unsafe.Pointer]sID
 	containers containers
 
@@ -167,9 +172,12 @@ type Serializer struct {
 }
 
 func newSerializer() *Serializer {
+	types := newTypeMap(serdes, nil)
+
 	return &Serializer{
 		serdes:   serdes,
-		types:    newTypeMap(serdes, nil),
+		types:    types,
+		funcs:    newFuncMap(types, nil),
 		ptrs:     make(map[unsafe.Pointer]sID),
 		scanptrs: make(map[reflect.Value]struct{}),
 		b:        make([]byte, 0, 128),
diff --git a/types/types.go b/types/types.go
index 0f24cea..3f29b31 100644
--- a/types/types.go
+++ b/types/types.go
@@ -336,6 +336,70 @@ func (m *typemap) ToType(t reflect.Type) typeid {
 	return id
 }
 
+type funcid = uint32
+
+type funcmap struct {
+	types *typemap
+
+	funcs []*coroutinev1.Function
+	cache doublemap[typeid, *Func]
+}
+
+func newFuncMap(types *typemap, funcs []*coroutinev1.Function) *funcmap {
+	return &funcmap{
+		types: types,
+		funcs: funcs,
+	}
+}
+
+func (m *funcmap) register(f *coroutinev1.Function) typeid {
+	m.funcs = append(m.funcs, f)
+	id := funcid(len(m.funcs)) // note that IDs start at 1
+	return id
+}
+
+func (m *funcmap) lookup(id funcid) *coroutinev1.Function {
+	if id == 0 || id > uint32(len(m.funcs)) {
+		return nil
+	}
+	return m.funcs[id-1]
+}
+
+func (m *funcmap) ToFunc(id funcid) *Func {
+	if x, ok := m.cache.getK(id); ok {
+		return x
+	}
+	cf := m.lookup(id)
+	if cf == nil {
+		panic(fmt.Sprintf("function ID %d not found", id))
+	}
+	f := FuncByName(cf.Name)
+	if f == nil {
+		panic(fmt.Sprintf("function %s not found", cf.Name))
+	}
+	return f
+}
+
+func (m *funcmap) RegisterAddr(addr unsafe.Pointer) (id funcid, closureType reflect.Type) {
+	f := FuncByAddr(uintptr(addr))
+	if f == nil {
+		panic(fmt.Sprintf("function not found at address %v", addr))
+	}
+
+	var closureTypeID typeid
+	if f.Closure != nil {
+		closureTypeID = m.types.ToType(f.Closure)
+	}
+
+	id = m.register(&coroutinev1.Function{
+		Name:    f.Name,
+		Type:    int32(m.types.ToType(f.Type)),
+		Closure: int32(closureTypeID),
+	})
+
+	return id, f.Closure
+}
+
 type doublemap[K, V comparable] struct {
 	fromK map[K]V
 	fromV map[V]K
diff --git a/types/unsafe.go b/types/unsafe.go
index 3213809..b100a5b 100644
--- a/types/unsafe.go
+++ b/types/unsafe.go
@@ -19,6 +19,12 @@ type slice struct {
 	cap  int
 }
 
+// Used for unsafe access to a function pointer and closure vars.
+type function struct {
+	addr unsafe.Pointer
+	// closure vars follow...
+}
+
 // returns true iff type t would be inlined in an interface.
 func inlined(t reflect.Type) bool {
 	switch t.Kind() {