[cvs-nhc98] Fix "head []" bug - the unit value () was to blame.

malcolm: Thu Jun 13 17:51:30 CEST 2002 Update of /usr/src/master/nhc/src/hat/tools In directory hinken:/tmp/cvs-serv4688 Modified Files: SExp.hs Log Message: Fix "head []" bug - the unit value () was to blame.