struct sexp;
struct sexp_list;

/* The Syntax checker is in charge
 * of checking that all syntactic forms are correctly adoperated.
 * TODO: In the future this will be part of the macro expander.
 * 
 * If there is any syntax error, an error message is printed to stderr the program is aborted.
 */
void check_syntax(struct sexp *s);

void check_program(struct sexp_list *prog);