Proposed final adjustments for CASL semantics

[pdmosses@brics.dk]

Dear subscribers to cofi-language@brics.dk:

The appended message concerns a proposal for some changes to the
details of the semantics of the following language constructs:

 * free datatype declarations;

 * default fitting arguments and imports; and

 * semantic annotations.  

The changes affect the well-formedness of CASL specifications.  If
adopted, they will require a new version of the language (1.0.2), as
well as a new release of the language summary.

Those who were involved in the design of CASL are asked to take a look
at the preliminary document summarizing the changes, which is
currently being circulated on the semantics mailing list (see the
appended message).  When the formal proposal for the changes to the
language and its summary are submitted, it will be announced on the
language design mailing list, and there will then be a period of 14
days to raise objections to the adoption of the various changes.

It seems appropriate to take the opportunity to fine-tune also the
rules about where comments and annotations can be inserted in CASL
specifications.  Some new miscellaneous annotations (e.g. for author
and date) are also being considered for inclusion in the new version
of the language.  A proposal with the details should appear at the
same time as the formal proposal for changes to the language
semantics.

If you're aware of further details of the language that are in need of
adjusting, please send a brief message to this mailing list,
explaining what problems have been experienced, indicating exactly
which language constructs would be affected, and sketching what
changes would be needed in wording of the CASL Summary.

Thank you for your attention to these matters!

-- Peter Mosses (Language Design Coordinator)

Till Mossakowski writes:

Dear friends,

during the last one or two years, a number of necessary small
adjustments to the CASL semantics have come up. They mainly 
arose from practical examples and/or proof attempts, and have been
discussed among some people involved with the CASL semantics.
The impact of these adjustments to the CASL language summary has 
been summarized under

http://www.informatik.uni-bremen.de/~till/Adaptions.ps

The impact on the semantics can be seen in the new version of
the semantics for structured specifications, available under

http://www.informatik.uni-bremen.de/~till/struct1.ps

(the changes to basic many-sorted and subsorted semantics
 still need to be done, but are rather straightforward).

Please send any immediate comments or objections to this until

  *** October the 6th ***

to cofi-semantics@brics.dk. This will then lead to a formal proposal
for the adjustment of the design (together with a proposal for some
adaptions of the (positions of) annotations, which will be treated in 
a forthcoming message).

Greetings,
Till

-- 
Till Mossakowski                Phone +49-421-218-4683
Dept. of Computer Science       Fax +49-421-218-3054
University of Bremen            till@tzi.de           
P.O.Box 330440, D-28334 Bremen  http://www.informatik.uni-bremen.de/~till