Using Fortran in Lua

The flu_binding also includes the interfaces to functions, required to incorporate your Fortran code in Lua scripts. A related project to this approach is Numeric Lua, that exposes standard numeric libraries to Lua. If you intend to use your Fortran implementations in such a way, embedding them in a Lua script you can do this by using Aotus and compiling your Fortran code together with it into a library.

To register Fortran functions for usage in Lua, you need to define a luaopen_libname function and call flu_register, for each function to expose to Lua.

Here is an example for this setup:

module libtest

  use, intrinsic :: iso_c_binding
  use flu_binding

  implicit none


  function luaopen_libtest(lua_state) result(val) bind(c)

      type(c_ptr), value :: lua_state
      integer(c_int) :: val
      type(flu_state) :: fL

      fL = flu_copyptr(lua_state)

      call flu_register(fL, "hello_f90", hello_f90)

      val = 0

  end function luaopen_libtest

  function hello_f90(lua_state) result(val) bind(c)

      use aotus_module

      type(c_ptr), value :: lua_state
      integer(c_int) :: val
      integer :: x, err
      type(flu_state) :: fL

      fL = flu_copyptr(lua_state)
      write (6,*) "HELLO FROM FORTRAN! :-)"
      call flu_pushinteger(fL, 102)
      call flu_setglobal(fL, "af90")
      val = 0

  end function hello_f90
end module libtest

After compilation of this code it could be used in Lua like this:

$ lua -e "require('libtest'); hello_f90(); print(af90)"

Resulting in: