`Bugs'

1.  tag closures so that they are inherited in subshells.  This would
    make some things a little more natural.

2.  Make es tail recursive.  In addition to being a Right Thing, this
    could be useful for reducing the number of primitives.   The only
    difficulty here is making sure that the interaction with the garbage 
    collector is done correctly.

`Neat ideas'

1.  Exposing `%parse' in both trivial and non-trivial ways.  The
    non-trivial ways might amount to some sort of macro system or
    something else.  I am not really sure.