No disagreement with most of what you've written, but 'while' and 'do/while' have different purposes. I suppose that it can be considered a matter of preference, but IMO, forcing one to serve the purpose of the other is a bit square-block-into-round-hole-ish. :)

do {
  print "Please enter $THING_TO_VALIDATE";
  chomp($input = <STDIN>);
} while THING_IS_NOT_VALID();
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