For several years in the early nineties the late Michael Downes presented 
a series of TeX macro programming challenges he called Around the Bend. These
were archived on CTAN in info/aro-bend, but are now in info/challenges/aro-bend,
as 36 files called exercise.* and answer.*, but in general Around the Bend 
is not well known even though it illuminates some of the essential, but 
possibly more arcane, aspects of TeX. 

    I have been presumptuous and taken the liberty of putting them all into
a single document, AroundTheBend.pdf,  which might be more accessible than 
the individual postings that form the original archive. I have also included 
three challenges, namely 19, 20, and 21, that have not made it into the 
CTAN archive.

   If Michael was still with us I imagine that he would have put no 
restrictions on his work. With this in mind, the files comprising 
AroundTheBend.tex, which is the basis for AroundTheBend.pdf, are under 
the LPPL.

Peter Wilson
25 July 2008