There's a fair bit of work to do for this idea, but here it is 'on the back of an envelope':

- overload the eval routine using exporter.

- your own eval routine needs to substitute 'exit' with 'return'.

- you therefore need yet another routine in a separate module which does not import your custom eval routine so that you can call it up to do the final (real) eval after the substitution has taken place.

Update: All this of course assuming there is a reasonable reason for trapping the exit only if its in an eval.