MLton not quite safe-for-space

[Henry Cejtin]

I  don't know if my CPS conversion is really the result of an optimization or
not, but I agree one could make the argument that it does.

I would have thought that there would be  some  movement  required  when  you
realize  that  a  call  is  never going to return.  Any way, it certainly has
never come up in anything I have done.   It  was  just  the  result  of  some
thinking  about  if there are any cases where a stack-based implementation is
costing us.  It was partly inspired by some comment  some  where  about  some
SML/NJ code which required the author to add these non-terminating loops just
so that SML/NJ would realize that the continuation was dead.   I  think  that
putting  it  on the todo list at low priority is probably the right place for
it.  Also I don't think I would like any overhead at non-GC time.