guile/libguile/gh_test_repl.c

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/* gh_test_repl -- a program that demonstrates starting Guile, adding
   some privmitive procedures and entering a REPL form C */

#include <stdio.h>
#include <math.h>

#include <gh.h>

SCM c_factorial (SCM s_n);
SCM c_sin (SCM s_x);
SCM c_vector_test (SCM s_length);

/* the gh_enter() routine, the standard entryp point for the gh_
   interface, makes you use a separate main function */
void 
main_prog (int argc, char *argv[])
{
  SCM cf;

  gh_eval_str ("(display \"hello guile\n\")");

  gh_eval_str ("(define (square x) (* x x))");
  gh_eval_str ("(define (fact n) (if (= n 1) 1 (* n (fact (- n 1)))))");

  gh_eval_str ("(display (square 9)) (newline)");
  gh_eval_str ("(display (fact 100)) (newline)");

  gh_eval_str ("(define s \"A string\")");
  gh_eval_str ("(define p '(A . pair))");
  gh_eval_str ("(display s)");
  gh_eval_str ("(display p)");
  gh_eval_str ("(display (string? s))");
  gh_eval_str ("(display (pair? s))");

  /* now define some new primitives in C */
  cf = gh_new_procedure1_0 ("c_factorial", c_factorial);
  gh_new_procedure1_0 ("c_sin", c_sin);
  gh_new_procedure1_0 ("c_vector_test", c_vector_test);

  /* now try some (eval ...) action from C */
  {
    SCM l = SCM_EOL;
    l = gh_cons (gh_str02scm ("hello world"), l);
    l = gh_cons (gh_symbol2scm ("'display"), l);
    gh_display (l);
  }

  {
    SCM a_string;
    a_string = gh_str02scm ("A string");

    printf ("testing the predicates for pair? and string?\n");
    printf ("gh_pair_p(a_string) is %d, gh_string_p(a_string) is %d\n",
	    gh_pair_p (a_string), gh_string_p (a_string));
  }

  printf ("testing the predicates for procedure? and vector?\n");
  printf ("gh_procedure_p(c_factorial) is %d, gh_vector_p(c_factorial) is %d\n",
	  gh_procedure_p (cf), gh_vector_p (cf));

  gh_repl ();
}

int 
main (int argc, char *argv[])
{
  gh_enter (argc, argv, main_prog);
  return 0;
}

SCM 
c_factorial (SCM s_n)
{
  int i, n;
  unsigned long result = 1;

  n = gh_scm2ulong (s_n);

  for (i = 1; i <= n; ++i)
    {
      result = result * i;
    }
  return gh_ulong2scm (result);
}

/* a sin routine in C, callable from scheme.  it is named c_sin() to
   distinguish it from the default scheme sin function */
SCM 
c_sin (SCM s_x)
{
  double x = gh_scm2double (s_x);

  return gh_double2scm (sin (x));
}

/* play around with vectors in guile: this routine creates a vector of
   the given length, initializes it all to zero except element 2 which
   is set to 1.9. */
SCM 
c_vector_test (SCM s_length)
{
  SCM xvec;
  unsigned long c_length;

  c_length = gh_scm2ulong (s_length);
  printf ("requested length for vector: %ld\n", c_length);

  /* create a vector filled witth 0.0 entries */
  xvec = gh_vector (c_length, gh_double2scm (0.0));
  /* set the second element in it to some floating point value */
  gh_vset (xvec, 2, gh_double2scm (1.9));

  return xvec;
}