a-module.rkt

#lang my-lang

(provide (all-defined-out))

(define (a-binding-to-a-function x)
  (list "this is in a function with" x "being the first argument"))

(printf "In Racket: module instantiated: ~s\n" (a-binding-to-a-function 'arg))

(define a-value 12354)

;; By default, this should print 12354
a-value

custom_dsl.cpp

/*
raco ctool --cgc --c-mods base.c ++lib racket/base ++lib racket/runtime-config ++lib my-lang ++lib my-lang/lang/reader
g++ -framework Foundation -I<RACKET-HEAD-REPO>/racket/include -L<RACKET-HEAD-REPO>/racket/src/build/racket -L<RACKET-HEAD-REPO>/racket/src/build/rktio custom_dsl.cpp -o custom_dsl -lracket -lmzgc -lrktio -liconv
./custom_dsl ./a-module.rkt
 */
#include <scheme.h>
#include <iostream>

#include "base.c"

static int run(Scheme_Env *e, int argc, char *argv[])
{
  Scheme_Object *curout;
  int i;
  Scheme_Thread *th;
  mz_jmp_buf * volatile save, fresh;

  /* Declare embedded modules in "base.c": */
  declare_modules(e);
  scheme_namespace_require(scheme_intern_symbol("my-lang"));

  curout = scheme_get_param(scheme_current_config(),
      MZCONFIG_OUTPUT_PORT);

  th = scheme_get_current_thread();

  save = th->error_buf;
  th->error_buf = &fresh;
  if (scheme_setjmp(*th->error_buf)) {
    th->error_buf = save;
    return -1; /* There was an error */
  } else {
    std::cout << "Trying to load file from \"" << argv[1] << "\"\n";
    Scheme_Object *custom_dsl_path[2];
    custom_dsl_path[0] = scheme_make_pair(
                           scheme_intern_symbol("file"),
                           scheme_make_pair(
                             scheme_make_utf8_string(argv[1]),
                             scheme_make_null()));
    custom_dsl_path[1] = scheme_make_false();
    Scheme_Object *custom_dsl = scheme_dynamic_require(2, custom_dsl_path);
    th->error_buf = save;
  }
  return 0;
}


int main(int argc, char **argv) {
  std::cout << "In cpp main\n";
  return scheme_main_setup(1, run, argc, argv);
}

log.txt

$ raco ctool --cgc --c-mods base.c ++lib racket/base ++lib racket/runtime-config ++lib my-lang ++lib my-lang/lang/reader

$ g++ -framework Foundation -I<RACKET-HEAD-REPO>/racket/include -L<RACKET-HEAD-REPO>/racket/src/build/racket -L<RACKET-HEAD-REPO>/racket/src/build/rktio custom_dsl.cpp -o custom_dsl -lracket -lmzgc -lrktio -liconv
ld: warning: could not create compact unwind for _ffi_call_unix64: does not use RBP or RSP based frame

$ ./custom_dsl ./a-module.rkt 
In cpp main
Trying to load file from "./a-module.rkt"
'(provide (all-defined-out))
'(define (a-binding-to-a-function x) (list "this is in a function with" x "being the first argument"))
'(printf "In Racket: module instantiated: ~s\n" (a-binding-to-a-function 'arg))
'(define a-value 12354)
'a-value