truth of ()

[Morris Katz <mkatz@sesame.stanford.edu>]

   Date: Fri, 26 May 89 13:55:27 edt
   From: Jonathan Rees <jar@zohar.ai.mit.edu>
   Reply-To: jar@zurich.ai.mit.edu


   There was no objection to the proposal that the truth behavior of the
   empty list be unspecified the last two times that the issue came up on
   this list, so I request that you make this change for R4RS.

   [Review of this issue:

   1. R3RS specifies that the empty list must be treated as false by
   conditionals.

   2. The question of ()'s truth was on the agenda for the Snowbird
   meeting but we didn't get around to discussing it.

   3. Someone requested that we require empty list and false to be
   distinct objects.  This request was rejected at Snowbird on
   compatibility grounds.

   4. Someone requested that the empty list MUST be treated as true.
   This is possible only if empty list and false are necessarily
   distinct, and this is not the case.]


I strongly agree with this proposal.  I just want to remind thos concerned that
someone should make a quick pass through 3.95 to make sure that all functions
are specified to return the correct choice between the empty list and #f.
					Morry Katz
					katz@polya.stanford.edu