paragraph-at-once justification (was Groff vs Heirloom troff)

[Doug McIlroy]

> often Tex just failed and overset lines.

Yes, TeX's curious policy of doing something terribly if
it can't be done well has led me to turn on \sloppy mode
by default, because "sloppy" is better than wrong.

Which brings me to another probable quibble with Knuth-
Plass. The "simple optimal text formatter" fmt claims
to use a variant of Knuth-Plass on equal-width fonts.
Often, the peculiar rules of a length "goal" distinct
from the length bound result in a paragraph that
looks worse than the simple greedy fill that nroff
employs. Moreover, with an "optimal" width being
chosen for each paragraph separately, you get pages
where the line-length appears to vary by paragraph.

Is the annoying behavior of fmt an artifact of its
variant of Knuth-Plass, or does TeX behave equally
capriciously on constant-width unjustified text?

Doug