Re: Making (DIFFERENCE 3) be -3

[PRATT@MIT-AI]

It would however be nice to have a generic operator that corresponded to
the fixnum and flonum operators in their behavior at one argument.
One possibility is to take MINUS to be that function.  This would be
an upward compatible change since on one argument MINUS would behave as
before.  Furthermore, MINUS seems a much better name for the opposite
of PLUS than DIFFERENCE, both in terms of length and the fact that one
always thinks of PLUS and MINUS.

If MINUS is not the way to go, some unused name should be brought into
play, perhaps DIFF or somesuch.  But I like the MINUS solution much better.