[racket] anamorphic macros

IMHO, a Racket way would more likely be to avoid bad hygiene, by one of:

* Just doing it as a procedure that takes closures for the `yes`and `no` 
arguments (with the `yes` one taking arguments for `head` and `tail`).

* Doing it as syntax, but having the user of the extension define the .  
(This might seem overkill, but maybe that's because that's because the 
original macro is already overkill.)

For Racket, I think presenting a non-hygienic problem is counterproductive.

BTW, you are to be commended for asking about this.  I hope you will 
join the Don't Use Eval Club.
http://lists.racket-lang.org/users/archive/2014-July/063597.html

Neil V.