[J3] sequence type equality

[Vipul Parekh]

On Thu, Oct 15, 2020 at 8:22 AM Bill Long via J3 <j3 at mailman.j3-fortran.org>
wrote:

> BIND(C) types solve the problem of interacting with C.   Modules solve he
> problem of “same type as”.  COMMON is obsolescent and better replaced by
> modules.   I don’t see any ue for SEQEUNCE types any more, except that
> really old codes might have them (as well as arithmetic IF and a lot of
> other ancient junk).   Is there any use for SEQUENCE that does not already
> have a batter alternative? ..
>

How will marking SEQUENCE as Obsolescent be of any help with the immediate
issue at hand which is the hole indicated by Bob when it comes to PURE
procedures?  Given the importance of PURE in modern programming using
Fortran, isn't really the choice here to either strive to plug this hole or
let the risk remain?

Marking something as Obsolescent does not mean the feature can be ignored
in any real sense, right?  Meaning, the semantics and/or syntax associated
with such a feature can continue to have impact on other existing features
and also the new ones.  Fixed-form source, marked as Obsolescent, is a
classic example: one can see the work on Conditional Expressions and the
syntax for that needs to critically consider the fixed-form source also.
This same aspect applies to everything on the Obsolescent list.

Until something is Deleted, all features including the Obsolescent ones
effectively seem to remain as "first-class" in the standard, don't they!?.

This does distress me in that the Obsolescent category seems just a label
in the standard.

So now, can SEQUENCE be deleted?  Does it not appear likely ever, right!

To do something here, like when two derived types with SEQUENCE attribute
be considered the same type, is the plug that can fill the gap brought
forth by Bob.

None of this is to suggest SEQUENCE should not be marked as Obsolescent,
just that it is a separate consideration.

Vipul Parekh
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