Dear Maude Abusers,

A new alpha release can be accessed at SRI-CSL in:

~eker/public_html/Maude/Alpha84b/

or downloaded from:

http://www.csl.sri.com/~eker/Maude/Alpha84b/

Alpha release site authentication:

User Name: maudeabuser
Password: bughunter

This version reports itself as Maude 2.1.1 and will be released as
such if no show stoppers are found in the next week or so. It is
intended as bug fix release. Currently there are no Darwin or FreeBSD
binaries because of configuration issues on our Darwin and FreeBSD
servers - hopefully this will be fixed by next week.

Bug fixes
==========
(1) A bug where upModule() generated the wrong meta-hooks for special
operators of classes ACU_NumberOpSymbol and CUI_NumberOpSymbol. This
also shows up with the "show all" command. Reported by Nathalie
Sznajder and Paco.

(2) A bug whether certain legal label names such as sort could not be
parsed in label renamings.

(3) The situation where two ad hoc overloaded operators have the same
domain kinds but different ranges now causes a warning to be emitted
as does the case where the arities differ but might look the same
because of associativity:

fmod FOO is
  sorts Foo Bar .
  op f : Foo -> Foo .
  op f : Foo -> Bar .
endfm

fmod BAR is
  sorts Foo Bar .
  op f : Foo Foo -> Foo [assoc] .
  op f : Foo Foo Foo -> Bar .
endfm

These cases are illegal but are handled correctly at the object
level. They always break the metalevel because of ambiguity and this
needs to be made clear in the manual. This inconsistancy was reported
by Nathalie Sznajder and Olaf Owe.

(4) There is now rudimentary checking of the consistancy for bubble
hooks since users are expected write these themselves; Thanks to
Fabricio Chalub for pointing out that the previous version crashes on
(bad) examples from the manual.

(5) A bug where an module with a missing identity could be imported,
causing an internal error:

fmod M is
  sort S .
  op __ : S S -> S [assoc id: ] .
endfm

fmod N is
  pr M .
endfm

Reported by Kazuhiro Ogata.

Other changes
==============
(1) Symmetric with
  set include FOO on/off .
we now have
  set protect FOO on/off .
and
  set extend FOO on/off .
A module may only be auto-imported in one mode. Furthermore the
prelude is changed so that BOOL is now auto-protected rather than
auto-included.

(2) Syntax for theories is supported. Currently this is mostly
syntactic sugar except that the rules for importation that we agreed
upon in Barcelona are now enforced by warnings and the module type of
a summation is correctly calculated. Basically we have a lattice:

      th
     /  \
   fth  mod
     \  /
     fmod

where summation corresponds to join and a module may only import a
module of less or equal type. Furthermore theories may only be
imported via the including importation mode. Theories are reflected by
constructors: fth_is_sorts_.____endfth and th_is_sorts_._____endth
The are now extra subsorts: SModule FTheory STheory. Module is now
used as the top sort rather than to represent system modules. This
choice was made to avoid breaking stuff that expects Module to be the
most general sort. The subsort relations are:
  subsorts FModule < SModule < Module .
  subsorts FTheory < STheory < Module .

  op [_] : Qid -> Module .
is redefined so that it works with all kinds of modules without
producing warnings.

(3) The surface parser now supports overparsing - i.e. it deliberately
parses more than the legal syntax in order to recover gracefully from
common errors. Currently it recognizes rls/crls in fmods/fths,
theories and modules terminated with the wrong keyword and the
missing space before the period ending a statement. In order to make
this possible there are minor restrictions on the legal syntax which
should only affect pathological examples:

  <    ->    ~>
are prohibited as sort names.

Tokens ending in a period in the rhs of a eq/rl/mb or the condition
of a ceq/crl/cmb cannot be followed by a keyword unless
they are inside of parentheses; eg the following is not allowed:
  eq c = d. eq .
It must be rewritten as
  eq c = (d. eq) .

Steven