Automatic Conversion

[Mark L. Miller <MILLER at MIT-AI>]

cc: BUG-LISP at MIT-AI, BUG-LISPM at MIT-AI, EJS at MIT-MC, H at MIT-MC,
    KMP at MIT-MC, HENRY at MIT-MC

Why not a several stage conversion process as follows:
0.  The current state of affairs (one DO supports both old and new).
1.  Rename the current function POSSIBLE-OLD-STYLE-DO and keep supporting it.
    Users wanting automatic upwards-compatibility can use MM REPLACE to
    change their current code to that.  (Using Query Replace, one could even
    optionally chose to NOT rename obviously-new-style DO's.)
    POSSIBLE-OLD-STYLE-DO would do what DO does now, but be autoloading
    and not necessarily efficient.  Keep current DO also for a while.
2.  Redefine DO to support only the new style after much warning.
3.  Eventually delete the autoload property for POSSIBLE-OLD-STYLE-DO from the
    default environment.
This sort of scheme might turn out to be useful for other changes as well.
Regards, Mark