Yes, you must provide an expression that returns a true or false value, and sub calls are expressions. 
while (more(...)) {
   ...
}

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while (!done(...)) {
   ...
}

[download]
while (my $item = get(...)) {
   ...
}

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In reply to Re: User defined function in while loop by ikegami
in thread User defined function in while loop by kgherman

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