In Common Lisp, multilevel returns use catch and throw; exception handling in the style of most other modern languages uses handler-case and error. Show that the distinction between these is mainly a...

In Common Lisp, multilevel returns use catch and throw; exception handling in the style of most other modern languages uses handler-case and

error. Show that the distinction between these is mainly a matter of style,

rather than expressive power. In other words, show that each facility can be

used to emulate the other.

char* days[7] = {"Sunday", "Monday", "Tuesday",

"Wednesday", "Thursday", "Friday", "Saturday"};

char today[10];

void handler(int n) {

printf(" %s\n", today);

}

int main() {

signal(SIGTSTP, handler); // ^Z at keyboard

for(int n = 0; ; n++) {

strcpy(today, days[n%7]);

}

}

Figure 9.6 A problematic program in C to illustrate the use of signals. In most Unix systems,

the SIGTSTP signal is generated by typing control-Z at the keyboard.