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(guile-tut.info)learn1.c

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learn1.c
--------

  Here is `learn1.c':
     #include <stdio.h>
     
     #include <guile/gh.h>
     
     #include "c_builtins.h"
     
     void main_prog(int argc, char *argv[]);
     
     main(int argc, char *argv[])
     {
       gh_enter(argc, argv, main_prog);
     }
     
     void main_prog(int argc, char *argv[])
     {
       char input_str[200];		/* ugly hack: assume strlen(line) < 200 */
       int done;
     
       /* for fun, evaluate some simple Scheme expressions here */
       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("(square 9)");
       gh_eval_str("(fact 100)");
     
       /* now try to define some new builtins, coded in C, so that they are
          available in Scheme. */
       gh_new_procedure1_0("c-factorial", c_factorial);
       gh_new_procedure1_0("c-sin", c_sin);
       gh_new_procedure1_0("v-t", vector_test);
     
       /* now sit in a Scheme eval loop: I input the expressions, have
          Guile evaluate them, and then get another expression.  */
       done = 0;
       fputs("learn1> ", stdout);
       while (!done) {
         if (gets(input_str) == NULL) {
           done = 1;
         } else {
           gh_eval_str(input_str);
           fputs("learn1> ", stdout);
         }
       }
     
       exit(0);
     }