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Re: Restricting the procedures to proper lists



Olin Shivers writes:
> For me, the current BIG QUESTION is this: some list-processing procedures
> do not always examine the whole list -- such as the procedures that search
> lists, like FIND, MEMBER, etc. Suppose we decide to restrict these
> procedures to proper lists. What is the spec going to be for invocations
> where the procedure never examines the whole list, and so cannot see the
> terminator? ...

What about simply:

"It is an error to apply these procedures to non-proper lists unless
it can be proved (in the problem space), that the list tail is never
reached."

Where "it is an error" has the usual technical meaning.

So it would be stated explicitly that the procedures in question may
(and should) complain, but not prematurely. I believe that's as close
as one can get.

W.