Add erlang:loaded/0 NIF

A more memory effective way of getting loaded modules (on BEAM),
used by Elixir 1.20

Add erlang:loaded/0 which returns a list of all currently loaded modules, matching the OTP behavior.

Changes:
Implement erlang:loaded/0 NIF in nifs.c
Register in nifs.gperf
Add Erlang stub with edoc in estdlib/erlang.erl
Add test test_erlang_loaded
Update CHANGELOG

Signed-off-by: Peter M <petermm@gmail.com>

Author: petermm

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Added a limited implementation of the OTP `ets` interface
 - Added `code:all_loaded/0` and `code:all_available/0`
+- Added `erlang:loaded/0`
 - Added `erlang:split_binary/2`
 - Added `inet:getaddr/2`
 - Added support for external pids and encoded pids in external terms

libs/estdlib/src/erlang.erl

@@ -52,6 +52,7 @@
     erase/0,
     erase/1,
     function_exported/3,
+    loaded/0,
     module_loaded/1,
     display/1,
     list_to_atom/1,
@@ -670,6 +671,15 @@ erase(_Key) ->
 function_exported(_Module, _Function, _Arity) ->
     erlang:nif_error(undefined).
 
+%%-----------------------------------------------------------------------------
+%% @returns list of loaded modules
+%% @doc     Returns all loaded modules.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec loaded() -> [module()].
+loaded() ->
+    erlang:nif_error(undefined).
+
 %% @param   Module name of module
 %% @returns boolean
 %% @doc     Returns true if module is loaded without attempting to do it.

src/libAtomVM/nifs.c

@@ -265,6 +265,7 @@ static term nif_code_server_type_resolver(Context *ctx, int argc, term argv[]);
 static term nif_code_server_import_resolver(Context *ctx, int argc, term argv[]);
 static term nif_code_server_set_native_code(Context *ctx, int argc, term argv[]);
 #endif
+static term nif_erlang_loaded(Context *ctx, int argc, term argv[]);
 static term nif_erlang_module_loaded(Context *ctx, int argc, term argv[]);
 static term nif_erlang_nif_error(Context *ctx, int argc, term argv[]);
 #ifndef AVM_NO_JIT
@@ -849,6 +850,10 @@ static const struct Nif code_server_set_native_code_nif = {
     .nif_ptr = nif_code_server_set_native_code
 };
 #endif
+static const struct Nif erlang_loaded_nif = {
+    .base.type = NIFFunctionType,
+    .nif_ptr = nif_erlang_loaded
+};
 
 static const struct Nif module_loaded_nif = {
     .base.type = NIFFunctionType,
@@ -5946,6 +5951,25 @@ static term nif_code_server_set_native_code(Context *ctx, int argc, term argv[])
 }
 #endif
 
+static term nif_erlang_loaded(Context *ctx, int argc, term argv[])
+{
+    UNUSED(argc);
+    UNUSED(argv);
+
+    term result = term_nil();
+    int loaded_modules_count = ctx->global->loaded_modules_count;
+    if (UNLIKELY(memory_ensure_free(ctx, LIST_SIZE(loaded_modules_count, 0)) != MEMORY_GC_OK)) {
+        RAISE_ERROR(OUT_OF_MEMORY_ATOM);
+    }
+
+    for (int ix = 0; ix < loaded_modules_count; ix++) {
+        Module *module = globalcontext_get_module_by_index(ctx->global, ix);
+        result = term_list_prepend(module_get_name(module), result, &ctx->heap);
+    }
+
+    return result;
+}
+
 static term nif_erlang_module_loaded(Context *ctx, int argc, term argv[])
 {
     UNUSED(argc);

src/libAtomVM/nifs.gperf

@@ -149,6 +149,7 @@ erlang:setnode/3, &setnode_3_nif
 erlang:dist_ctrl_get_data_notification/1, &dist_ctrl_get_data_notification_nif
 erlang:dist_ctrl_get_data/1, &dist_ctrl_get_data_nif
 erlang:dist_ctrl_put_data/2, &dist_ctrl_put_data_nif
+erlang:loaded/0, &erlang_loaded_nif
 erlang:module_loaded/1,&module_loaded_nif
 erlang:nif_error/1,&nif_error_nif
 erlang:list_to_bitstring/1, &list_to_bitstring_nif

tests/erlang_tests/CMakeLists.txt

@@ -590,6 +590,7 @@ compile_erlang(test_close_avm_pack DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/code_load
 
 compile_erlang(test_module_info)
 compile_erlang(erlang_module_loaded)
+compile_erlang(test_erlang_loaded)
 
 compile_erlang(int64_build_binary)
 
@@ -1153,6 +1154,7 @@ set(erlang_test_beams
 
     test_module_info.beam
     erlang_module_loaded.beam
+    test_erlang_loaded.beam
 
     int64_build_binary.beam
 

tests/erlang_tests/test_erlang_loaded.erl

@@ -0,0 +1,38 @@
+%
+% This file is part of AtomVM.
+%
+% Copyright 2026 AtomVM Contributors
+%
+% Licensed under the Apache License, Version 2.0 (the "License");
+% you may not use this file except in compliance with the License.
+% You may obtain a copy of the License at
+%
+%    http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS,
+% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+% See the License for the specific language governing permissions and
+% limitations under the License.
+%
+% SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+%
+
+-module(test_erlang_loaded).
+
+-export([start/0]).
+
+start() ->
+    Loaded = erlang:loaded(),
+    true = is_list(Loaded),
+    true = length(Loaded) > 0,
+    true = contains(?MODULE, Loaded),
+    true = all_atoms(Loaded),
+    0.
+
+contains(_Module, []) -> false;
+contains(Module, [Module | _]) -> true;
+contains(Module, [_H | Tail]) -> contains(Module, Tail).
+
+all_atoms([]) -> true;
+all_atoms([H | Tail]) -> is_atom(H) andalso all_atoms(Tail).

tests/test.c

@@ -562,6 +562,7 @@ struct Test tests[] = {
 
     TEST_CASE(test_module_info),
     TEST_CASE(erlang_module_loaded),
+    TEST_CASE(test_erlang_loaded),
 
     TEST_CASE(test_op_bs_start_match),
     TEST_CASE(test_op_bs_create_bin),