How can I return success or failure to the operating system in Haskell?

Question

The simplest Unix tools are true and false, little programs that do nothing but return 0 and 1 respectively to the operating system and exit. An example in C might look like the below:

// true - does nothing successfully
int main(void) {
  return 0;
}

Through searching, I haven't been able to find a way to implement this kind of functionality in Haskell. Is there anything in the IO monad that can do this?

Answer 1

Use one of the functions defined in System.Exit.

Answer 2

See System.Exit.