Re: Issue: ADJUST-ARRAY-NOT-ADJUSTABLE (Version 6)

[Jeff Dalton <jeff%aiai.edinburgh.ac.uk@NSS.Cs.Ucl.AC.UK>]

>   The description of ADJUST-ARRAY on pp297-298 says that it is
>   ``not permitted to call ADJUST-ARRAY on an array that was not
>   created with the :ADJUSTABLE option.'' This is inconsistent with
>   ADJUSTABLE-ARRAY-P.

Well, the other sections don't say anything explicitly, and this one
does; so why doesn't this one take precedence?

>   Specifying the points left unspecified (requiring all simple arrays to be
>   non-adjustable and all adjustable arrays to be non-simple) would require
>   large changes to some implementations and would be of little benefit to
>   users, merely making one kind of nonconforming program fail in all
>   implementations instead of failing only in some implementations. 

This is kind of strange.  I think it's a good thing when nonconforming
programs fail everywhere, and not something we should just dismiss.
We should allow such differences only when there are good reasons to
do so.

>   Users
>   need to know that certain arrays are simple, so they can put in
>   declarations and get higher performance, but users have no need to be
>   able to create arrays that are definitely non-simple (for lower
>   performance) or definitely non-adjustable (to cause errors).

Surely the performance of an array with certain characteristics
is the same whether or not we say it's simple.  So creating arrays
that are definitely non-simple is not a request for lower performance.

>   Pitman wishes some of the other proposals were economically feasible to
>   pursue but reluctantly agrees that maintaining (and clearly documenting)
>   the status quo is probably the most reasonable avenue left to us.

Sigh.