determined the string will not exceed the column width. But
output is the caller environment's output state variable. A
better choice is output-default.
In two places (length+ form) is replaced with (or (length+ form) +inf.0)
so that arithmetic can be performed on the result.
To support cyclic structures in pretty-simply (wrapped with
trimmed/lazy), the call-with-output form in pp-with-indent needs to be
wrapped with an appropriate trimmed/lazy.
In pp-pair, call (pp (car ls)) instead of (pretty (car ls)).
In pretty-simply, don't use call-with-output, that prevents
(trimmed/lazy n (pretty-simply ...)) from working at all on cyclic
input.
