lists

[Andrew Wright <wright@cs.rice.edu>]

It appears my earlier message is going to be easily misinterpreted.

My point is that the R4RS seems to be a bit schizophrenic about what
a list is.  On the one hand, there are "proper lists", which are
finite length, nil terminated, and tested for by list?  On the other
hand, there are {\it list}s that are used as domain specifiers for
the inputs to various procedures like list-tail and member.  As
David Carlton remarks, we don't want to make list-tail, member, etc.
more expensive by requiring them to test that their argument is
a "proper list".  Perhaps the section about errors and domain extension
that David quotes is enough, but I think the description of lists could
be made a bit clearer on this point.

Andrew