Here's another bit that seems a bit confusing...

The approach does allow references to variable names with “-”
embedded in them without effort,
but the names must be spelled differently (and thus inconsistently)
by replacing every “-” with “_”.
Thus, variables like “list-ref” must
be spelled as “list_ref” inside the infix.plt notation
without effort.

In particular the last "without effort" there seems to be something
that got left behind in some edit.

I also think that the bit "The approach does allow references to
variable names with '-' embedded in them without effort," should be
"little effort" instead, as it's not actually *without* effort, users
having to translate - to _ after all.