A C-like if statement

[Roy Smith]

In article <pan.2006.02.24.11.07.19.764837 at REMOVETHIScyber.com.au>,
 Steven D'Aprano <steve at REMOVETHIScyber.com.au> wrote:

> Side-effects aren't always bad (import, for example, does all its work by
> side-effect). But they are generally frowned upon, and in functional
> languages they are verboten.

How do you do any I/O in a functional language if side effects are 
verboten?  For that matter, how does a functional program ever stop running?