non-null termination of list

[Dave Touretzky <Dave.Touretzky at CMU-10A>]

With *RSET on, the mapping functions check for lists that don't end in
NIL, and signal an error if appropriate.  The error is signalled on the
*RSET user interrupt channel.  I think it would be better to signal on
another channel, such as WRNG-TYPE-ARG.  The reason is that most *RSET
interrupts are really trivial *RSET-traps that FIXIT (the CMU MacLisp
debugger) throws away.  The only exception I am aware of is the non-null 
termination of list error signalled by MAPC and friends.  In this case
the user probably does want to enter a debug loop so he can look at the
list in error.  The easiest fix appears to be to change the mapping
functions to signal their errors on a "serious" interrupt channel
instead of the catch-all one.

Yes, I realize that since the test is controlled by *RSET it is correct to
signal on the *RSET channel, or at least it seems reasonable to do so.  But
give my suggestion some thought anyway.

-- Dave Touretzky