#define scm_first SCM_CAR
#define scm_tail SCM_CDR
#define scm_c_define_procedure_c_init SCM scm_c_define_procedure_c_temp;
#define scm_is_undefined(a) (SCM_UNDEFINED == a)

/** defines and registers a c routine as a scheme procedure with documentation.
    like scm-c-define-gsubr but also sets documentation.
    scm-c-define-procedure-c-init must have been called in scope */
#define scm_c_define_procedure_c(name, required, optional, rest, c_function, documentation) \
  scm_c_define_procedure_c_temp = scm_c_define_gsubr(name, required, optional, rest, c_function); \
  scm_set_procedure_property_x(scm_c_define_procedure_c_temp, (scm_from_locale_symbol("documentation")), (scm_from_locale_string(documentation)))

/** SCM SCM c-compound-expression ->
    iterate over scm-list in c */
#define scm_c_list_each(list, e, body) \
  while (!scm_is_null(list)) { \
    e = scm_first(list); \
    body; \
    list = scm_tail(list); \
  }

/** display value with scheme write and add a newline */
void scm_debug_log(SCM value) {
  scm_call_2((scm_variable_ref((scm_c_lookup("write")))), value, (scm_current_output_port()));
  scm_newline((scm_current_output_port()));
}

/** creates a new bytevector of size-octects that contains the given bytevector */
SCM scm_c_bytevector_take(size_t size_octets, uint8_t* a) {
  SCM r = scm_c_make_bytevector(size_octets);
  memcpy((SCM_BYTEVECTOR_CONTENTS(r)), a, size_octets);
  return (r);
}