Re: An m4 puzzlement.

Thanks for your reply to my message.

  Underquoted, although it doesn't affect the particular issue you raised.

Yes; I whittled the example from the more complex version I'm actually using.
After poking around a bit with quoting, I assumed it wasn't causing the problem
(always a risky assumption to make), and used only the quoting necessary to
make this example work.

  the real problem is that m4 (unfortunately) does not understand [[:alpha:]]
  yet, and is instead treating your regex as exactly one byte from [:[ahlp],
  followed by any number (including 0) of a literal ]*; 'a' matches that regex,
  but 'b' does not.

Alas, yes.  I was lulled into a false sense of security when I figured out that
+ worked.  I naively assumed that posix character classes would work too.