[exeldapp]

Not sure if that example helps. You can make any programming language hard to read without some basic formatting. The way I would write the sexpr would be:

  (impl
    (impl 
       p 
       (impl q r))
    (impl
       (impl p q)
       (impl p r)))

It's clear when each section begins and ends and doesn't require complex parsing rules.

[tearflake]

That looks clean, can't argue that.