$ -parallel +pretty
Above, except that if the last line of the first argument stops at least one position before the first line of the second begins, these two lines are overlapped. For example:
> text "hi" $$ nest 5 (text "there")
lays out as
> hi there
$$ is associative, with identity empty, and also satisfies
* (x $$ y) <> z = x $$ (y <> z), if y non-empty.
Above, with no overlapping. $+$ is associative, with identity empty.