feat: add module mp_units

example/CMakeLists.txt

@@ -22,15 +22,25 @@
 
 cmake_minimum_required(VERSION 3.5)
 
+# find dependencies
+if(NOT TARGET gsl::gsl-lite)
+    find_package(gsl-lite CONFIG REQUIRED)
+endif()
+
 add_library(example_utils INTERFACE)
 target_include_directories(example_utils INTERFACE include)
+target_link_libraries(example_utils INTERFACE gsl::gsl-lite)
 
 #
-# add_example(target <depependencies>...)
+# add_example(target <mp-units-depependencies>...)
 #
 function(add_example target)
     add_executable(${target} ${target}.cpp)
-    target_link_libraries(${target} PRIVATE ${ARGN})
+    if(TARGET mp-units::modules)
+        target_link_libraries(${target} PRIVATE mp-units::modules)
+    else()
+        target_link_libraries(${target} PRIVATE ${ARGN})
+    endif()
 endfunction()
 
 add_example(avg_speed mp-units::core-io mp-units::si mp-units::cgs mp-units::usc)
@@ -49,7 +59,8 @@ add_example(
 add_example(conversion_factor mp-units::core-fmt mp-units::core-io mp-units::si)
 add_example(currency mp-units::core-io)
 add_example(foot_pound_second mp-units::core-fmt mp-units::international mp-units::imperial)
-add_example(glide_computer mp-units::core-fmt mp-units::international mp-units::utility glide_computer_lib)
+add_example(glide_computer mp-units::core-fmt mp-units::international mp-units::utility)
+target_link_libraries(glide_computer PRIVATE glide_computer_lib)
 add_example(hello_units mp-units::core-fmt mp-units::core-io mp-units::si mp-units::usc)
 add_example(measurement mp-units::core-io mp-units::si)
 add_example(si_constants mp-units::core-fmt mp-units::si)
@@ -60,14 +71,9 @@ add_example(
 )
 add_example(total_energy mp-units::core-io mp-units::si mp-units::natural mp-units::utility)
 add_example(
-    unmanned_aerial_vehicle
-    mp-units::core-fmt
-    mp-units::core-io
-    mp-units::si
-    mp-units::international
-    mp-units::utility
-    example_utils
+    unmanned_aerial_vehicle mp-units::core-fmt mp-units::core-io mp-units::si mp-units::international mp-units::utility
 )
+target_link_libraries(unmanned_aerial_vehicle PRIVATE example_utils)
 
 add_subdirectory(glide_computer_lib)
 add_subdirectory(kalman_filter)

example/avg_speed.cpp

@@ -25,13 +25,17 @@
 // !!! renders correctly in the documentation "Examples" section.                 !!!
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
+#include <exception>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/ostream.h>
 #include <mp-units/systems/cgs/cgs.h>
 #include <mp-units/systems/international/international.h>
-#include <mp-units/systems/isq/isq.h>
-#include <mp-units/systems/si/si.h>
-#include <exception>
-#include <iostream>
+#include <mp-units/systems/isq/space_and_time.h>
+#include <mp-units/systems/si/unit_symbols.h>
+#endif
 
 namespace {
 

example/capacitor_time_curve.cpp

@@ -20,11 +20,15 @@
     physical_quantities
 */
 
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/math.h>  // IWYU pragma: keep
 #include <mp-units/ostream.h>
 #include <mp-units/systems/isq/electromagnetism.h>
 #include <mp-units/systems/si/si.h>
-#include <iostream>
+#endif
 
 int main()
 {

example/clcpp_response.cpp

@@ -15,6 +15,11 @@
  along with this program. If not, see http://www.gnu.org/licenses./
 */
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/ostream.h>
 #include <mp-units/systems/iau/iau.h>
@@ -24,7 +29,7 @@
 #include <mp-units/systems/si/si.h>
 #include <mp-units/systems/typographic/typographic.h>
 #include <mp-units/systems/usc/usc.h>
-#include <iostream>
+#endif
 
 namespace {
 

example/conversion_factor.cpp

@@ -15,12 +15,17 @@
  along with this program. If not, see http://www.gnu.org/licenses./
 */
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <iostream>
+#include <type_traits>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
 #include <mp-units/systems/si/units.h>
-#include <iostream>
-#include <type_traits>
+#endif
 
 /*
   get conversion factor from one dimensionally equivalent

example/currency.cpp

@@ -20,11 +20,16 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <mp-units/quantity_spec_macro.h>
+#include <iostream>
+#include <map>
+#ifdef MP_UNITS_MODULES
+import mp_units.core_io;
+#else
 #include <mp-units/ostream.h>
 #include <mp-units/quantity.h>
 #include <mp-units/quantity_point.h>
-#include <iostream>
-#include <map>
+#endif
 
 using namespace mp_units;
 

example/foot_pound_second.cpp

@@ -20,14 +20,19 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <iostream>
+#include <string_view>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/imperial/imperial.h>
 #include <mp-units/systems/international/international.h>
 #include <mp-units/systems/isq/mechanics.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <iostream>
-#include <string_view>
+#endif
 
 using namespace mp_units;
 using namespace mp_units::international::unit_symbols;

example/glide_computer.cpp

@@ -22,10 +22,6 @@
 
 #include "glide_computer_lib.h"
 #include <mp-units/bits/fmt_hacks.h>
-#include <mp-units/chrono.h>
-#include <mp-units/math.h>
-#include <mp-units/systems/international/international.h>
-#include <mp-units/systems/si/unit_symbols.h>
 #include <array>
 #include <exception>
 #include <iostream>
@@ -33,6 +29,14 @@
 #include <string>
 #include <utility>
 #include <vector>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
+#include <mp-units/chrono.h>
+#include <mp-units/math.h>
+#include <mp-units/systems/international/international.h>
+#include <mp-units/systems/si/unit_symbols.h>
+#endif
 
 namespace {
 

example/glide_computer_lib/CMakeLists.txt

@@ -23,5 +23,10 @@
 cmake_minimum_required(VERSION 3.5)
 
 add_library(glide_computer_lib STATIC glide_computer_lib.cpp include/glide_computer_lib.h)
-target_link_libraries(glide_computer_lib PRIVATE mp-units::core-fmt PUBLIC mp-units::si mp-units::utility example_utils)
+if(TARGET mp-units::modules)
+    target_link_libraries(glide_computer_lib PUBLIC gsl::gsl-lite mp-units::modules)
+else()
+    target_link_libraries(glide_computer_lib PRIVATE mp-units::core-fmt PUBLIC mp-units::si mp-units::utility)
+endif()
+target_link_libraries(glide_computer_lib PUBLIC example_utils)
 target_include_directories(glide_computer_lib PUBLIC include)

example/glide_computer_lib/glide_computer_lib.cpp

@@ -21,10 +21,14 @@
 // SOFTWARE.
 
 #include "glide_computer_lib.h"
-#include <mp-units/format.h>
 #include <iostream>
 #include <numeric>
 #include <string_view>
+#ifdef MP_UNITS_MODULES
+import mp_units.core_fmt;
+#else
+#include <mp-units/format.h>
+#endif
 
 namespace glide_computer {
 

example/glide_computer_lib/include/glide_computer_lib.h

@@ -22,11 +22,9 @@
 
 #pragma once
 
+#include <mp-units/quantity_spec_macro.h>
+//
 #include "geographic.h"
-#include <mp-units/chrono.h>
-#include <mp-units/math.h>  // IWYU pragma: keep
-#include <mp-units/quantity_point.h>
-#include <mp-units/systems/isq/space_and_time.h>
 #include <algorithm>
 #include <array>
 #include <initializer_list>
@@ -35,6 +33,14 @@
 #include <ranges>
 #include <string>  // IWYU pragma: keep
 #include <vector>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
+#include <mp-units/chrono.h>
+#include <mp-units/math.h>  // IWYU pragma: keep
+#include <mp-units/quantity_point.h>
+#include <mp-units/systems/isq/space_and_time.h>
+#endif
 
 // An example of a really simplified tactical glide computer
 // Simplifications:

example/hello_units.cpp

@@ -25,12 +25,17 @@
 // !!! renders correctly in the documentation "Examples" section.                 !!!
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/ostream.h>
 #include <mp-units/systems/international/international.h>
 #include <mp-units/systems/isq/isq.h>
 #include <mp-units/systems/si/si.h>
-#include <iostream>
+#endif
 
 using namespace mp_units;
 

example/include/geographic.h

@@ -24,6 +24,13 @@
 
 #include "ranged_representation.h"
 #include <mp-units/bits/fmt_hacks.h>
+#include <compare>
+#include <limits>
+#include <numbers>
+#include <ostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/compare.h>
 #include <mp-units/format.h>
 #include <mp-units/math.h>
@@ -31,10 +38,7 @@
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/units.h>
-#include <compare>
-#include <limits>
-#include <numbers>
-#include <ostream>
+#endif
 
 namespace geographic {
 

example/include/ranged_representation.h

@@ -24,11 +24,15 @@
 
 #include "validated_type.h"
 #include <mp-units/bits/external/hacks.h>
-#include <mp-units/bits/fmt.h>
-#include <mp-units/customization_points.h>
 #include <algorithm>
 #include <concepts>
 #include <type_traits>
+#ifdef MP_UNITS_MODULES
+import mp_units.core;
+#else
+#include <mp-units/bits/fmt.h>
+#include <mp-units/customization_points.h>
+#endif
 
 template<std::movable T, MP_UNITS_CONSTRAINED_NTTP_WORKAROUND(std::convertible_to<T>) auto Min,
          MP_UNITS_CONSTRAINED_NTTP_WORKAROUND(std::convertible_to<T>) auto Max>

example/include/validated_type.h

@@ -23,11 +23,16 @@
 #pragma once
 
 #include <gsl/gsl-lite.hpp>
+#include <mp-units/bits/fmt_hacks.h>
+#include <ostream>
+#include <utility>
+#ifdef MP_UNITS_MODULES
+import mp_units.core_fmt;
+#else
 #include <mp-units/bits/external/hacks.h>
 #include <mp-units/bits/fmt.h>
 #include <mp-units/customization_points.h>
-#include <ostream>
-#include <utility>
+#endif
 
 inline constexpr struct validated_tag {
 } validated;

example/kalman_filter/CMakeLists.txt

@@ -27,7 +27,11 @@ cmake_minimum_required(VERSION 3.5)
 #
 function(add_example target)
     add_executable(${target} ${target}.cpp)
-    target_link_libraries(${target} PRIVATE ${ARGN})
+    if(TARGET mp-units::modules)
+        target_link_libraries(${target} PRIVATE mp-units::modules)
+    else()
+        target_link_libraries(${target} PRIVATE ${ARGN})
+    endif()
 endfunction()
 
 add_example(kalman_filter-example_1 mp-units::core-fmt mp-units::si mp-units::utility)

example/kalman_filter/kalman.h

@@ -23,12 +23,16 @@
 #pragma once
 
 #include <mp-units/bits/fmt_hacks.h>
+#include <tuple>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/math.h>
 #include <mp-units/quantity.h>
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/space_and_time.h>
-#include <tuple>
+#endif
 
 namespace kalman {
 

example/kalman_filter/kalman_filter-example_1.cpp

@@ -21,11 +21,15 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/alphabeta.html#ex1
 

example/kalman_filter/kalman_filter-example_2.cpp

@@ -21,11 +21,15 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/alphabeta.html#ex2
 

example/kalman_filter/kalman_filter-example_3.cpp

@@ -21,11 +21,15 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/alphabeta.html#ex3
 

example/kalman_filter/kalman_filter-example_4.cpp

@@ -21,11 +21,15 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/alphabeta.html#ex4
 

example/kalman_filter/kalman_filter-example_5.cpp

@@ -21,12 +21,16 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/math.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/kalman1d.html#ex5
 

example/kalman_filter/kalman_filter-example_6.cpp

@@ -21,13 +21,17 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/math.h>
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/thermodynamics.h>
 #include <mp-units/systems/si/si.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/kalman1d.html#ex6
 

example/kalman_filter/kalman_filter-example_7.cpp

@@ -21,13 +21,17 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/math.h>
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/thermodynamics.h>
 #include <mp-units/systems/si/si.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/kalman1d.html#ex7
 

example/kalman_filter/kalman_filter-example_8.cpp

@@ -21,13 +21,17 @@
 // SOFTWARE.
 
 #include "kalman.h"
+#include <array>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/math.h>
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/thermodynamics.h>
 #include <mp-units/systems/si/si.h>
-#include <array>
-#include <iostream>
+#endif
 
 // Based on: https://www.kalmanfilter.net/kalman1d.html#ex8
 

example/measurement.cpp

@@ -20,13 +20,17 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <cmath>
+#include <exception>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/ostream.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
 #include <mp-units/systems/si/units.h>
-#include <cmath>
-#include <exception>
-#include <iostream>
+#endif
 
 namespace {
 

example/si_constants.cpp

@@ -25,9 +25,14 @@
 // !!! renders correctly in the documentation "Examples" section.                 !!!
 // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/si/si.h>
-#include <iostream>
+#endif
 
 template<class T>
   requires mp_units::is_scalar<T>

example/spectroscopy_units.cpp

@@ -20,11 +20,16 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <iostream>
+#include <tuple>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/format.h>
 #include <mp-units/systems/isq/isq.h>
 #include <mp-units/systems/si/si.h>
-#include <iostream>
-#include <tuple>
+#endif
 
 // This example implements a table of units provided in the following article
 // http://cds.cern.ch/record/1481609/files/978-3-642-18018-7_BookBackMatter.pdf

example/storage_tank.cpp

@@ -20,6 +20,16 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <mp-units/bits/fmt_hacks.h>
+#include <mp-units/quantity_spec_macro.h>
+#include <cassert>
+#include <chrono>
+#include <iostream>
+#include <numbers>
+#include <utility>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/chrono.h>
 #include <mp-units/format.h>
 #include <mp-units/math.h>
@@ -28,11 +38,7 @@
 #include <mp-units/systems/si/constants.h>
 #include <mp-units/systems/si/unit_symbols.h>
 #include <mp-units/systems/si/units.h>
-#include <cassert>
-#include <chrono>
-#include <iostream>
-#include <numbers>
-#include <utility>
+#endif
 
 // allows standard gravity (acceleration) and weight (force) to be expressed with scalar representation
 // types instead of requiring the usage of Linear Algebra library for this simple example

example/strong_angular_quantities.cpp

@@ -20,11 +20,15 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/math.h>
 #include <mp-units/ostream.h>
 #include <mp-units/systems/isq_angle/isq_angle.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <iostream>
+#endif
 
 template<class T>
   requires mp_units::is_scalar<T>

example/total_energy.cpp

@@ -20,14 +20,18 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#include <exception>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/math.h>
 #include <mp-units/ostream.h>
 #include <mp-units/systems/isq/mechanics.h>
 #include <mp-units/systems/natural/natural.h>
 #include <mp-units/systems/si/constants.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <exception>
-#include <iostream>
+#endif
 
 template<class T>
   requires mp_units::is_scalar<T>
@@ -56,31 +60,21 @@ void si_example()
 
   std::cout << "\n*** SI units (c = " << c << " = " << c.in(si::metre / s) << ") ***\n";
 
-  std::cout << "\n[in `GeV` and `c`]\n"
-            << "p = " << p1 << "\n"
-            << "m = " << m1 << "\n"
-            << "E = " << E << "\n";
+  std::cout << "\n[in `GeV` and `c`]\n" << "p = " << p1 << "\n" << "m = " << m1 << "\n" << "E = " << E << "\n";
 
   const auto p2 = p1.in(GeV / (m / s));
   const auto m2 = m1.in(GeV / pow<2>(m / s));
   const auto E2 = total_energy(p2, m2, c).in(GeV);
 
-  std::cout << "\n[in `GeV`]\n"
-            << "p = " << p2 << "\n"
-            << "m = " << m2 << "\n"
-            << "E = " << E2 << "\n";
+  std::cout << "\n[in `GeV`]\n" << "p = " << p2 << "\n" << "m = " << m2 << "\n" << "E = " << E2 << "\n";
 
   const auto p3 = p1.in(kg * m / s);
   const auto m3 = m1.in(kg);
   const auto E3 = total_energy(p3, m3, c).in(J);
 
-  std::cout << "\n[in SI base units]\n"
-            << "p = " << p3 << "\n"
-            << "m = " << m3 << "\n"
-            << "E = " << E3 << "\n";
+  std::cout << "\n[in SI base units]\n" << "p = " << p3 << "\n" << "m = " << m3 << "\n" << "E = " << E3 << "\n";
 
-  std::cout << "\n[converted from SI units back to GeV]\n"
-            << "E = " << E3.force_in(GeV) << "\n";
+  std::cout << "\n[converted from SI units back to GeV]\n" << "E = " << E3.force_in(GeV) << "\n";
 }
 
 void natural_example()

example/unmanned_aerial_vehicle.cpp

@@ -21,13 +21,18 @@
 // SOFTWARE.
 
 #include "geographic.h"
+#include <mp-units/bits/fmt_hacks.h>
+#include <cassert>
+#include <iostream>
+#ifdef MP_UNITS_MODULES
+import mp_units;
+#else
 #include <mp-units/ostream.h>
 #include <mp-units/quantity_point.h>
 #include <mp-units/systems/international/international.h>
 #include <mp-units/systems/isq/space_and_time.h>
 #include <mp-units/systems/si/unit_symbols.h>
-#include <cassert>
-#include <iostream>
+#endif
 
 using namespace mp_units;
 using namespace geographic;