[plt-scheme] determine free variables

Sam TH writes:
 > On Mon, Mar 24, 2008 at 8:42 PM, Jay McCarthy <jay.mccarthy at gmail.com> wrote:
 > > Look at collects/web-server/lang/freevars.ss for a (syntax -> (listof
 > >  identifier-syntax)) function
 > 
 > There's also an implementation (intended for use in other libraries)
 > in syntax/free-vars (maybe the webserver should use that?).

I also implemented this for my dissertation language:

http://socrates-lang.cvs.sourceforge.net/socrates-lang/socrates/free-vars.ss?revision=1.5

--dougorleans at gmail.com