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DELFILE, thanks to DWIM

Apart from the failure to ask if you wanted the "correction" GETFILE into
DELFILE, there is also the question of why DELFILE was happy with the
extra argument (in your example, 'SIZE).  Common Lisp programs have the
notion of argument-number checking, and many spurious forms like
(DELFILE 'FOO.BAR 'SIZE) would be rejected at that level.

Argument-number checking isn't completely incompatible with Interlisp --
or at least the use of Interlisp without unwarranted DWIM interference.
All that would be required is the breaking of the rather dubious contract
that *all* functions must have *all* arguments in the category of "optional
and defaulting to NIL".

Totaly leaving aside the question of backwards compatibility with all those
never-changing Interlisp programs dating back to the 1960's, it would be
instructive to know what percentage of current users feel that the current 
situation of *no* argment-number checking is completely satisfactory.   The 
alternative need not require explicity NIL's in calling code, since many 
functions may want some kind of &optional behaviour anyway.

-- JonL --