diff --git a/src/kernel/declaration.cpp b/src/kernel/declaration.cpp
index 177009ca88..4432a58006 100644
--- a/src/kernel/declaration.cpp
+++ b/src/kernel/declaration.cpp
@@ -14,13 +14,11 @@ extern "C" object * lean_mk_reducibility_hints_regular(uint32 h);
 extern "C" uint32 lean_reducibility_hints_get_height(object * o);
 
 reducibility_hints reducibility_hints::mk_regular(unsigned h) {
-    object * r = alloc_cnstr(static_cast<unsigned>(reducibility_hints_kind::Regular), 0, sizeof(unsigned));
-    cnstr_set_scalar<unsigned>(r, 0, h);
-    return reducibility_hints(r);
+    return reducibility_hints(lean_mk_reducibility_hints_regular(h));
 }
 
 unsigned reducibility_hints::get_height() const {
-    return is_regular() ? cnstr_get_scalar<unsigned>(raw(), 0) : 0;
+    return lean_reducibility_hints_get_height(to_obj_arg());
 }
 
 int compare(reducibility_hints const & h1, reducibility_hints const & h2) {
@@ -59,21 +57,20 @@ extern "C" object * lean_mk_axiom_val(object * n, object * lparams, object * typ
 extern "C" uint8 lean_axiom_val_is_unsafe(object * v);
 
 axiom_val::axiom_val(name const & n, names const & lparams, expr const & type, bool is_unsafe):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), 1)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*), static_cast<unsigned char>(is_unsafe));
+    object_ref(lean_mk_axiom_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), is_unsafe)) {
 }
 
-bool axiom_val::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)) != 0; }
+bool axiom_val::is_unsafe() const { return lean_axiom_val_is_unsafe(to_obj_arg()); }
 
 extern "C" object * lean_mk_definition_val(object * n, object * lparams, object * type, object * value, object * hints, uint8 is_unsafe);
 extern "C" uint8 lean_definition_val_is_unsafe(object * v);
 
 definition_val::definition_val(name const & n, names const & lparams, expr const & type, expr const & val, reducibility_hints const & hints, bool is_unsafe):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), val, hints, 1)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*3, static_cast<unsigned char>(is_unsafe));
+    object_ref(lean_mk_definition_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), val.to_obj_arg(),
+                                      hints.to_obj_arg(), is_unsafe)) {
 }
 
-bool definition_val::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*3) != 0; }
+bool definition_val::is_unsafe() const { return lean_definition_val_is_unsafe(to_obj_arg()); }
 
 theorem_val::theorem_val(name const & n, names const & lparams, expr const & type, expr const & val):
     object_ref(mk_cnstr(0, constant_val(n, lparams, type), object_ref(lean_task_pure(val.to_obj_arg())))) {
@@ -89,21 +86,19 @@ extern "C" object * lean_mk_opaque_val(object * n, object * lparams, object * ty
 extern "C" uint8 lean_opaque_val_is_unsafe(object * v);
 
 opaque_val::opaque_val(name const & n, names const & lparams, expr const & type, expr const & val, bool is_unsafe):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), val, 1)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*2, static_cast<unsigned char>(is_unsafe));
+    object_ref(lean_mk_opaque_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), val.to_obj_arg(), is_unsafe)) {
 }
 
-bool opaque_val::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*2) != 0; }
+bool opaque_val::is_unsafe() const { return lean_opaque_val_is_unsafe(to_obj_arg()); }
 
-extern "C" object * lean_mk_quot_val(object * n, object * lparams, object * type, object * value, uint8 k);
+extern "C" object * lean_mk_quot_val(object * n, object * lparams, object * type, uint8 k);
 extern "C" uint8 lean_quot_val_kind(object * v);
 
 quot_val::quot_val(name const & n, names const & lparams, expr const & type, quot_kind k):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), 1)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*), static_cast<unsigned char>(k));
+    object_ref(lean_mk_quot_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), static_cast<uint8>(k))) {
 }
 
-quot_kind quot_val::get_quot_kind() const { return static_cast<quot_kind>(cnstr_get_scalar<unsigned char>(raw(), sizeof(object*))); }
+quot_kind quot_val::get_quot_kind() const { return static_cast<quot_kind>(lean_quot_val_kind(to_obj_arg())); }
 
 recursor_rule::recursor_rule(name const & cnstr, unsigned nfields, expr const & rhs):
     object_ref(mk_cnstr(0, cnstr, nat(nfields), rhs)) {
@@ -117,18 +112,13 @@ extern "C" uint8 lean_inductive_val_is_reflexive(object * v);
 
 inductive_val::inductive_val(name const & n, names const & lparams, expr const & type, unsigned nparams,
                              unsigned nindices, names const & all, names const & cnstrs, bool rec, bool unsafe, bool is_refl):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), nat(nparams), nat(nindices), all, cnstrs, 3)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*5, static_cast<unsigned char>(rec));
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*5 + 1, static_cast<unsigned char>(unsafe));
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*5 + 2, static_cast<unsigned char>(is_refl));
-    lean_assert(is_unsafe() == unsafe);
-    lean_assert(is_rec() == rec);
-    lean_assert(is_reflexive() == is_refl);
+    object_ref(lean_mk_inductive_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), nat(nparams).to_obj_arg(),
+                                     nat(nindices).to_obj_arg(), all.to_obj_arg(), cnstrs.to_obj_arg(), rec, unsafe, is_refl)) {
 }
 
-bool inductive_val::is_rec() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*5) != 0; }
-bool inductive_val::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*5 + 1) != 0; }
-bool inductive_val::is_reflexive() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*5 + 2) != 0; }
+bool inductive_val::is_rec() const { return lean_inductive_val_is_rec(to_obj_arg()); }
+bool inductive_val::is_unsafe() const { return lean_inductive_val_is_unsafe(to_obj_arg()); }
+bool inductive_val::is_reflexive() const { return lean_inductive_val_is_reflexive(to_obj_arg()); }
 
 extern "C" object * lean_mk_constructor_val(object * n, object * lparams, object * type, object * induct,
                                             object * cidx, object * nparams, object * nfields, uint8 unsafe);
@@ -136,29 +126,28 @@ extern "C" uint8 lean_constructor_val_is_unsafe(object * v);
 
 constructor_val::constructor_val(name const & n, names const & lparams, expr const & type, name const & induct, unsigned cidx, unsigned nparams, unsigned
                                  nfields, bool is_unsafe):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), induct, nat(cidx), nat(nparams), nat(nfields), 1)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*5, static_cast<unsigned char>(is_unsafe));
+    object_ref(lean_mk_constructor_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), induct.to_obj_arg(),
+                                       nat(cidx).to_obj_arg(), nat(nparams).to_obj_arg(), nat(nfields).to_obj_arg(), is_unsafe)) {
 }
 
-bool constructor_val::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*5) != 0; }
+bool constructor_val::is_unsafe() const { return lean_constructor_val_is_unsafe(to_obj_arg()); }
 
 extern "C" object * lean_mk_recursor_val(object * n, object * lparams, object * type, object * all,
                                          object * nparams, object * nindices, object * nmotives, object * nminors,
                                          object * rules, uint8 k, uint8 unsafe);
-extern "C" uint8 lean_recursor_val_k(object * v);
-extern "C" uint8 lean_recursor_val_is_unsafe(object * v);
+extern "C" uint8 lean_recursor_k(object * v);
+extern "C" uint8 lean_recursor_is_unsafe(object * v);
 
 recursor_val::recursor_val(name const & n, names const & lparams, expr const & type,
                            names const & all, unsigned nparams, unsigned nindices, unsigned nmotives,
                            unsigned nminors, recursor_rules const & rules, bool k, bool is_unsafe):
-    object_ref(mk_cnstr(0, constant_val(n, lparams, type), all, nat(nparams), nat(nindices), nat(nmotives),
-                        nat(nminors), rules, 2)) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*7, static_cast<unsigned char>(k));
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*7 + 1, static_cast<unsigned char>(is_unsafe));
+    object_ref(lean_mk_recursor_val(n.to_obj_arg(), lparams.to_obj_arg(), type.to_obj_arg(), all.to_obj_arg(),
+                                    nat(nparams).to_obj_arg(), nat(nindices).to_obj_arg(), nat(nmotives).to_obj_arg(),
+                                    nat(nminors).to_obj_arg(), rules.to_obj_arg(), k, is_unsafe)) {
 }
 
-bool recursor_val::is_k() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*7) != 0; }
-bool recursor_val::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*7 + 1) != 0; }
+bool recursor_val::is_k() const { return lean_recursor_k(to_obj_arg()); }
+bool recursor_val::is_unsafe() const { return lean_recursor_is_unsafe(to_obj_arg()); }
 
 bool declaration::is_unsafe() const {
     switch (kind()) {
@@ -266,18 +255,14 @@ inductive_type::inductive_type(name const & id, expr const & type, constructors
     object_ref(mk_cnstr(0, id, type, cnstrs)) {
 }
 
-static unsigned inductive_decl_scalar_offset() { return sizeof(object*)*3; }
-
 extern "C" object * lean_mk_inductive_decl(object * lparams, object * nparams, object * types, uint8 unsafe);
 extern "C" uint8 lean_is_unsafe_inductive_decl(object * d);
 
 declaration mk_inductive_decl(names const & lparams, nat const & nparams, inductive_types const & types, bool is_unsafe) {
-    declaration r(mk_cnstr(static_cast<unsigned>(declaration_kind::Inductive), lparams, nparams, types, 1));
-    cnstr_set_scalar<unsigned char>(r.raw(), inductive_decl_scalar_offset(), static_cast<unsigned char>(is_unsafe));
-    return r;
+    return declaration(lean_mk_inductive_decl(lparams.to_obj_arg(), nparams.to_obj_arg(), types.to_obj_arg(), is_unsafe));
 }
 
-bool inductive_decl::is_unsafe() const { return cnstr_get_scalar<unsigned char>(raw(), inductive_decl_scalar_offset()) != 0; }
+bool inductive_decl::is_unsafe() const { return lean_is_unsafe_inductive_decl(to_obj_arg()); }
 
 // =======================================
 // Constant info
diff --git a/src/kernel/local_ctx.cpp b/src/kernel/local_ctx.cpp
index 9d0bce5f80..be8f2e7adc 100644
--- a/src/kernel/local_ctx.cpp
+++ b/src/kernel/local_ctx.cpp
@@ -20,12 +20,11 @@ extern "C" uint8 lean_local_decl_binder_info(object * d);
 local_decl::local_decl():object_ref(*g_dummy_decl) {}
 
 local_decl::local_decl(unsigned idx, name const & n, name const & un, expr const & t, expr const & v):
-    object_ref(mk_cnstr(1, nat(idx), n, un, t, v)) {
+    object_ref(lean_mk_let_decl(nat(idx).to_obj_arg(), n.to_obj_arg(), un.to_obj_arg(), t.to_obj_arg(), v.to_obj_arg())) {
 }
 
 local_decl::local_decl(unsigned idx, name const & n, name const & un, expr const & t, binder_info bi):
-    object_ref(mk_cnstr(0, nat(idx), n, un, t, sizeof(unsigned char))) {
-    cnstr_set_scalar<unsigned char>(raw(), sizeof(object*)*4, static_cast<unsigned char>(bi));
+    object_ref(lean_mk_local_decl(nat(idx).to_obj_arg(), n.to_obj_arg(), un.to_obj_arg(), t.to_obj_arg(), static_cast<uint8>(bi))) {
 }
 
 local_decl::local_decl(local_decl const & d, expr const & t, expr const & v):
@@ -35,8 +34,7 @@ local_decl::local_decl(local_decl const & d, expr const & t):
     local_decl(d.get_idx(), d.get_name(), d.get_user_name(), t, d.get_info()) {}
 
 binder_info local_decl::get_info() const {
-    if (cnstr_tag(raw()) == 0) return static_cast<binder_info>(cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*4));
-    else return binder_info();
+    return static_cast<binder_info>(lean_local_decl_binder_info(to_obj_arg()));
 }
 
 expr local_decl::mk_ref() const {
diff --git a/src/library/messages.cpp b/src/library/messages.cpp
index 819164a4fa..d2b9184f1c 100644
--- a/src/library/messages.cpp
+++ b/src/library/messages.cpp
@@ -15,17 +15,17 @@ extern "C" uint8 lean_message_severity(object * msg);
 
 message::message(std::string const & filename, pos_info const & pos, optional<pos_info> const & end_pos,
                  message_severity severity, std::string const & caption, std::string const & text) :
-    object_ref(mk_cnstr(0, string_ref(filename), position(pos),
-                        option_ref<position>(end_pos ? some(position(*end_pos)) : optional<position>()),
-                        string_ref(caption), string_ref(text), sizeof(message_severity))) {
-    cnstr_set_scalar(raw(), sizeof(void*) * 5, severity);
+    object_ref(lean_mk_message(string_ref(filename).to_obj_arg(), position(pos).to_obj_arg(),
+                               option_ref<position>(end_pos ? some(position(*end_pos)) : optional<position>()).to_obj_arg(),
+                               static_cast<uint8>(severity),
+                               string_ref(caption).to_obj_arg(), string_ref(text).to_obj_arg())) {
 }
 
 message::message(parser_exception const & ex) :
-        message(ex.get_file_name(), *ex.get_pos(), ERROR, ex.get_msg()) {}
+    message(ex.get_file_name(), *ex.get_pos(), ERROR, ex.get_msg()) {}
 
 message_severity message::get_severity() const {
-    return cnstr_get_scalar<message_severity>(raw(), sizeof(void*) * 5);
+    return static_cast<message_severity>(lean_message_severity(to_obj_arg()));
 }
 
 std::ostream & operator<<(std::ostream & out, message const & msg) {
diff --git a/src/library/metavar_context.cpp b/src/library/metavar_context.cpp
index ba8ac3e82d..027639aedf 100644
--- a/src/library/metavar_context.cpp
+++ b/src/library/metavar_context.cpp
@@ -19,8 +19,7 @@ static expr *       g_dummy_type;
 extern "C" object * lean_mk_metavar_decl(object * user_name, object * lctx, object * type, object * depth, object * local_insts, uint8 k);
 
 metavar_decl::metavar_decl(name const & user_name, local_context const & lctx, expr const & type):
-    object_ref(mk_cnstr(0, user_name, lctx, type, 1)) {
-    cnstr_set_scalar<uint8>(raw(), 3*sizeof(object*), false);
+    object_ref(lean_mk_metavar_decl(user_name.to_obj_arg(), lctx.to_obj_arg(), type.to_obj_arg(), nat(0).to_obj_arg(), box(0), 0)) {
 }
 
 metavar_decl::metavar_decl():
diff --git a/src/library/projection.cpp b/src/library/projection.cpp
index de448d70da..cae5d6201e 100644
--- a/src/library/projection.cpp
+++ b/src/library/projection.cpp
@@ -17,11 +17,10 @@ extern "C" object * lean_mk_projection_info(object * ctor_name, object * nparams
 extern "C" uint8 lean_projection_info_from_class(object * info);
 
 projection_info::projection_info(name const & c, unsigned nparams, unsigned i, bool inst_implicit):
-    object_ref(mk_cnstr(0, c, nat(nparams), nat(i))) {
-    cnstr_set_scalar<unsigned char>(raw(), 3*sizeof(object*), static_cast<unsigned char>(inst_implicit));
+    object_ref(lean_mk_projection_info(c.to_obj_arg(), nat(nparams).to_obj_arg(), nat(i).to_obj_arg(), inst_implicit)) {
 }
 
-bool projection_info::is_inst_implicit() const { return cnstr_get_scalar<unsigned char>(raw(), sizeof(object*)*3) != 0; }
+bool projection_info::is_inst_implicit() const { return lean_projection_info_from_class(to_obj_arg()); }
 
 extern "C" object* lean_add_projection_info(object* env, object* p, object* ctor, object* nparams, object* i, uint8 fromClass);
 extern "C" object* lean_get_projection_info(object* env, object* p);
diff --git a/src/util/kvmap.cpp b/src/util/kvmap.cpp
index 282fc849ae..4ba48acbc3 100644
--- a/src/util/kvmap.cpp
+++ b/src/util/kvmap.cpp
@@ -11,13 +11,12 @@ extern "C" object * lean_mk_bool_data_value(bool b);
 extern "C" uint8 lean_data_value_bool(object * v);
 
 data_value::data_value(bool v):
-    object_ref(alloc_cnstr(static_cast<unsigned>(data_value_kind::Bool), 0, 1)) {
-    cnstr_set_scalar<unsigned char>(raw(), 0, v);
+    object_ref(lean_mk_bool_data_value(v)) {
 }
 
 bool data_value::get_bool() const {
     lean_assert(kind() == data_value_kind::Bool);
-    return static_cast<bool>(cnstr_get_scalar<unsigned char>(raw(), 0));
+    return lean_data_value_bool(to_obj_arg());
 }
 
 bool operator==(data_value const & a, data_value const & b) {