Major Section: RELEASE-NOTES
NOTE! New users can ignore these release notes, because the documentation has been updated to reflect all changes that are recorded here.
Below we roughly organize the changes since Version 3.6.1 into the following categories of changes: existing features, new features, heuristic improvements, bug fixes, distributed books, Emacs support, and experimental versions. Each change is described in just one category, though of course many changes could be placed in more than one category. Also see note-3-6-1 for other changes since Version 3.6.
CHANGES TO EXISTING FEATURES
There have been extensive changes to the handling of compiled files for
books, which may generally be invisible to most users. The basic idea is
that when compiled files are loaded on behalf of
include-book, they are
now loaded before events in the book are processed, not afterwards. This can
speed up calls of
include-book, especially if the underlying Lisp
compiles all definitions on the fly (as is the case for CCL and SBCL). One
functional change is that for keyword argument
include-book, the values
:comp! are no
longer legal. (Note that the handling of
:comp-raw was actually broken,
so it seems that this value wasn't actually used by anyone; also, the
:comp! formerly could cause an error in some Lisp platforms,
including SBCL.) Another change is that if
include-book is called with
:load-compiled-file t, then each sub-book must have a compiled file or a
so-called ``expansion file''; see book-compiled-file. In the unlikely event
that this presents a problem, the makefile provides a way to build with
compilation disabled; see compilation. Users of raw mode
(see set-raw-mode) will be happy to know that
include-book now works
if there an up-to-date compiled file for the book, since
commands are now incorporated into that compiled file. The mechanism for
saving expansion files has changed, and the
:save-expansion argument of
certify-book has been eliminated; see certify-book. More discussion
of ACL2's new handling of book compilation is described in a new
documentation topic; see book-compiled-file.
It was possible to get a hard Lisp error when certifying a book with a
defconst form whose term is not identical to the existing
defconst form for the same name. The following example illustrates the
problem, which has been fixed (as part of the change in handling of compiled
files for books, described above). Imagine that after the initial
(in-package "ACL2") form, file
foo.lisp has just the form
(defconst *a* (append nil nil)). Then before the fix, we could have:
ACL2 !>(defconst *a* nil) [[output omitted]] ACL2 !>(certify-book "foo" 1) [[initial output omitted] * Step 5: Compile the functions defined in "/v/joe/foo.lisp". Compiling /v/joe/foo.lisp. End of Pass 1. End of Pass 2. OPTIMIZE levels: Safety=0 (No runtime error checking), Space=0, Speed=3 Finished compiling /vjoe/foo.lisp. Loading /v/joe/foo.lisp Error: Illegal attempt to redeclare the constant *A*.
wormhole facility has been changed to repair a bug that allowed
guard violations to go undetected. The major change has to do with the
treatment of what used to be called the ``pseudo-flag'' argument which has
been replaced by a quoted lambda expression. See note-4-0-wormhole-changes
for help in converting calls of
wormhole. Also see see wormhole and
assign-wormhole-output has been eliminated but its
functionality can be provided by
The ACL2 tutorial has been greatly expanded, for example to include a self-contained discussion of rewriting. See acl2-tutorial.
mbe macro and
must-be-equal function were
disallowed in any definition within an encapsulate having a non-empty
signature. Now, these are allowed provided the definition has been declared
to be non-executable (see defun-nx). As a result,
events may now include
must-be-equal among the function symbols
known by the evaluator; this had not previously been allowed. Thanks to Sol
Swords for discussions leading to this relaxation for
Princ$ now prints strings more efficiently. Thanks to Jared Davis for
suggesting the improvements to
The use of
:non-executable t no longer requires
the absence of
state or declared
stobjs among the formal
parameters of a function definition. As before, the use of
:non-executable t turns off single-threadedness checking for the body,
and also as before, attempts to execute the function will fail. Thanks to
Sol Swords for requesting this relaxation (for automatic generation of
so-called ``flag functions'' for definitions using
The documentation has been improved for explaining to advanced users the
details of the ACL2 hint mechanism; see hints-and-the-waterfall, and see the
nonlinearp-default-hint in distributed book
books/hints/basic-tests.lisp. Thanks to Robert Krug for useful
discussions, in particular suggesting the above example as one to be
explained with the documentation.
time$ macro has been enhanced to allow user control of the timing
message that is printed, and of when it is printed. See time$. Thanks to
Jared Davis for providing the essential design, helpful documentation
(largely incorporated), and an initial implementation for raw Lisp.
:ttags argument to
include-book had been required when
including a certified book that uses trust tags. This is no longer the case:
:ttags defaults to
:all except that warnings will be
printed. Thanks to Jared Davis for requesting such a relaxation, and to him
and Sandip Ray for useful discussions.
The definition of
mv-let has been modified so that the single-step
macroexpansion (see trans1) of its calls can be evaluated. Thanks to Pete
Manolios for bringing this evaluation issue to our attention and ensuing
All calls of so-called ``guard-holders'' --
must-be-equal (from calls of see mbe),
mv-list -- are now removed before storing hypotheses of rules of
linear. Thanks to Sol Swords for
requesting this enhancement and sending the following example in the case of
(defthm foo (prog2$ (cw "asdf") (and (equal (car (cons x y)) x) (equal (cdr (cons x y)) y))))
The handling of
~s has been modified so that if the
argument is a symbol that would normally be printed using vertical bars
|), then that symbol is printed as with
~f. Thanks to Jared Davis
for providing the following example showing that treatment of
~s was a
(cw "~s0.~%" '|fo\|o|).
Error messages have been improved for ill-formed terms (in ACL2's so-called ``translation'' routines). Thanks to Jared Davis for requesting such an enhancement.
defun-sk so that it executes in
Previously, evaluation of a
defun-sk event in
caused a somewhat inscrutable error, but now,
program mode is
treated the same as
logic mode for purposes of
The ``system hacker'' commands
) are now embedded event forms
(see embedded-event-form), hence may be used in books as well as in
encapsulate events. Also, these two commands are
now no-ops in raw Lisp.
The function symbol
worldp (in the
"ACL2" package) has been renamed
gc$-fn (resulting from macroexpansion of
gc$) is now
logic mode. Thanks to Jared Davis for requesting this change.
The user now has control over whether compilation is used, for example
whether or not
certify-book compiles by default, using function
set-compiler-enabled. See compilation.
Modified the conversion of relative to absolute pathnames in portcullis commands for book certification. Now, more pathnames remain as relative pathnames.
"Ttags" warning that can be printed by
include-book is now
given even if
set-inhibit-output-lst has specified `
suppress it, specify
warning! instead, for example,
(set-inhibit-output-lst '(acl2::warning! acl2::proof-tree)).
On occasion, ACL2 prints the message ``Flushing current installed world'' as
it cleans up when certain actions (installing a world) are interrupted.
This operation has been sped up considerably. If your session includes many
events, you can probably speed up any such operation further by invoking
reset-prehistory. Thanks to Jared Davis for sending a query that led
us to make this improvement.
Calls of the form
(ec-call (must-be-equal logic exec)) are no longer
allowed, since we do not have confidence that they would be handled
The underlying function for
good-bye (and hence for
quit) is now in
logic mode. Thanks to Jared Davis for
requesting this enhancement.
We now require that every function symbol in the signature of an
encapsulate event have a
logic mode definition at the end of
the first pass, not merely a
program mode definition (which
formerly was sufficient). You can still define such a function in
:program mode, provided it is followed by a
:logic mode definition
(where of course both definitions are local, since we are discussing
functions is introduced in the signature). Thanks to Carl Eastlund for
bringing this issue to our attention. (Note: An analogous modification has
been made for
bdd hints as well.)
The following functions now have raw Lisp implementations that may run faster
than their ACL2 definitions:
position-equal. Thanks to Jared Davis for suggesting that we consider
such an improvement.
We now avoid infinite loops caused when tracing functions that implement
trace$. Thanks to Rob Sumners and Eric Smith for useful discussions.
The implementation of
trace! has been modified slightly, to accommodate
the fix for ``some holes in the handling of trust tags'' described later,
This item applies unless the host Lisp is GCL. An interrupt (control-c) will
now cause a proof to exit normally in most cases, by simulating a timeout, as
with-prover-time-limit had been called with a time-limit of 0.
If the first interrupt doesn't terminate the proof, a second one should do so
(because a different, more ``severe'' mechanism is used after the first
attempt). As a result,
redo-flat should work as one might expect even
if a proof is interrupted. Thanks to Dave Greve for requesting this
redo-flat. Technical note: for reasons related to this
change, time-limits are no longer checked in evaluator functions
It is now legal for proof-checker macro-commands to appear in
instructions that are used in place of
to Sandip Ray for (most recently) requesting this feature.
The value of
ld special variable
ld-post-eval-print is now treated as though it were
t if the value
ld special variable
nil. The following
example illustrates this change.
ACL2 !>(ld-post-eval-print state) ; default :COMMAND-CONVENTIONS ACL2 !>(ld-error-triples state) ; default T ACL2 !>(set-ld-error-triples nil state) *** Then, before the change: ACL2 !>(mv t 3 state) 3 *** Instead, after the change: ACL2 !>(mv t 3 state) (T 3 <state>)
The default behavior of
ld has been changed. Formerly when an error
occurred that halted a subsidiary call of
ld, then the parent
would continue. That is no longer the case. Consider the following
(ld '((ld '((defun f (x) x) (defun bad (x)) ; ERROR -- missing the body )) (defun g (x) x)))Formerly,
gwould be defined in the resulting logical world. Now, the error halts not only the inner
ldbut also the outer
ld. See ld, and for details of the new default value for
:RETURN!, see see ld-error-action. Also see the paragraph below about a new utility,
p!. Thanks to Robert Krug and Sandip Ray for helpful discussions.
ACL2-CUSTOMIZATION has been replaced by
ACL2_CUSTOMIZATION -- that is, the hyphen has been replaced by an
underscore -- so that it can be set conveniently in the
Warnings:'' summary is now omitted when there are no warnings,
where formerly ``
Warnings: None'' was printed. Thanks to Jared Davis
for suggesting this change.
We have modified the generation of
events in two primary ways, neither of them likely to affect many users.
One change is that the virtual movement of definitions and theorems to in
front of an
encapsulate event, or of definitions to behind that event,
is no longer inhibited in the case of nested encapsulates with non-empty
signatures. The following example illustrates the other change, as
(encapsulate ((f (x) t)) (local (defun f (x) x)) (defun g (x) (cons x (f x))) (defun h (x) (g x)) (defthm h-is-f (equal (car (h x)) x)))Previously, the constraint on
hwas essentially the conjunction of the definition of
hand the theorem
h-is-f. Now, the definition of
gis conjoined as well; moreover,
greceives the same constraint as do
h, where previously
gwas only constrained by its definition. While we are not aware of a soundness bug caused by the previous approach, the new approach follows more precisely the intended notion of constraint.
The use of
:multiplicity had been
required when option
:native was supplied. This is no longer the case.
Also, a bug has been fixed that had prevented
:multiplicity from working
properly in GCL and Allegro CL.
Several errors have been eliminated that formerly occurred when the
constraints for a function symbol were unknown because it was constrained
using a dependent clause-processor (see define-trusted-clause-processor.
Now, it is assumed that the
supporters argument in a
define-trusted-clause-processor event is such that every ancestor of
any function symbol constrained by the ``promised encapsulate'' of that event
among, or ancestral in, those
supporters. Thanks to Sol Swords, Sandip
Ray, and Jared Davis for helpful discussions.
The notion of constraint for functions introduced by
been modified slightly. No longer do we remove from the body of the
definition calls of so-called ``guard-holders'':
must-be-equal, ec-call, and mv-list, and uses of
the-error generated by
the. Also, we now expand calls of
the-error with the same aggressive heuristics applied to a number of
other functions (technically, adding it to the list
A new event,
defattach, allows evaluation of calls of constrained
encapsulated) functions. In particular, users can now, in principle,
soundly modify ACL2 source code; please feel free to contact the ACL2
implementors if you are interested in doing so. See defattach.
Eric Smith has noticed that if you exit the break-rewrite loop using
a! during an
ld of a file, then all changes to the logical
world are discarded that were made during that call of
ld. A new
p!, pops just one level instead, and avoids discarding
that work. (This change is related to an item above, ``The default behavior
ld has been changed.'') Thanks to Eric for pointing out this issue.
mv-list is the identity function logically, but converts
multiple values to lists. The first argument is the number of values, so an
example form is as follows, where
foo returns three values:
(mv-list 3 (foo x y)). Thanks to Sol Swords for requesting this
feature and for reporting a soundness bug in one of our preliminary
state global variable,
host-lisp, has as its value a keyword
whose value depends on the underlying Common Lisp implementation. Use
(@ host-lisp) to see its value.
It is now possible to write documentation for HTML without error when
there are links to nonexistent documentation topics. See the comments in
acl2::write-html-file at the end of file
doc/write-acl2-html.lisp. When there are such errors, they should be
easier to understand than previously. Thanks to Alan Dunn for providing the
It is now possible to inhibit specified parts of the Summary printed at the
conclusion of an event. See set-inhibited-summary-types. Also
see with-output, in particular the discussion of the new
keyword. Thanks to Sol Swords for requesting more control over the Summary.
:case-split-limitations, can override the
default case-split-limitations settings (see set-case-split-limitations) in
the simplifier. Thanks to Ian Johnson for requesting this addition and
providing an initial implementation.
It is now possible to defer and avoid some ttag-related output; see set-deferred-ttag-notes. Thanks to Jared Davis for requesting less verbosity from ttag-related output.
A new command,
pl2, allows you to restrict the rewrite rules
printed that apply to a given term. See pl2. Thanks to Robert Krug for
requesting such a capability.
ACL2 now provides a utility for canonicalizing filenames, so that soft links
are resolved; see canonical-pathname. Moreover, ACL2 uses this utility in
its own sources, which can eliminate some issues. In particular,
include-book with argument
:ttags :all no longer breaks when given
a book name differing from the book name that was used at certification time;
thanks to Sol Swords for reporting that problem. Also, certain errors
have been eliminated involving the combination of packages in the
certification world and trust tags; thanks to Jared Davis for sending an
example of that problem.
You can now suppress or enable guard-checking for an individual form; see with-guard-checking. Thanks to Sol Swords for requesting this feature.
walkabout utility has been documented (thanks to Rob Sumners for
suggesting this documentation). This utility can make it easy to explore a
cons tree. New interactive commands
(pp n) and
(pp print-level print-length) have been added to restrict how much of the
current object is displayed. See walkabout.
Rules of class
type-prescription may now be provided a
:backchain-limit-lst keyword. The default behavior is unchanged, but now
type-set is sensitive not only to the new
:backchain-limit-lst of a
type-prescription rule (if
supplied) but to the
default-backchain-limit of the current logical
world. Setting of backchain-limits can now specify either the new
(type-set) limit or the old limit (for rewriting);
see set-default-backchain-limit and see set-backchain-limit. Moreover, the
backchain-limit now take a
second argument of
:rewrite to specify which backchain-limit
The so-called ``too-many-ifs'' heuristic has been modified. Such a heuristic
has been employed in ACL2 (and previous Boyer-Moore provers) for many years,
in order to limit the introduction of calls of
IF by non-recursive
functions. Most users need not be concerned with this change, but two proofs
in the regression suite (out of thousands) needed trivial adjustment, so user
proofs could need tweaking. In one application, this modification sped up
proofs by 15%; but the change in runtime for the regression suite is
negligible, so such speedups may vary. Thanks to Sol Swords for providing a
test from ACL2 runs at Centaur Technology, which was useful in re-tuning this
Guard proof obligations could have size quadratic in the number of clauses in
case statement. This inefficiency has been removed with a change
that eliminates a hypothesis of the form
(not (eql term constant)) when
there is already a stronger hypothesis, equating the same term with a
different constant. Thanks to Sol Swords for bringing this problem to our
attention and suggesting an alternate approach to solving it, which we may
consider in the future if related efficiency problems persist.
We adjusted the heuristics for determining induction schemes in the presence
of ruler-extenders, when handling calls of a function symbol that is a
ruler-extender, in either of two cases: either the function takes only one
argument; or the function is
ec-call, and the first
argument contains no recursive call. These cases are treated more directly
as though the ruler-extender call is replaced by the unique (in the case of
ec-call, the second) argument.
true-listp-append, has been
(implies (true-listp b) (true-listp (append a b)))If you are interested in the motivation for adding this rule, see comments in
true-listp-appendin ACL2 source file
The use of
:forward-chaining lemmas has been improved slightly. In
previous versions, a conclusion derived by forward chaining was discarded if
it was derivable by type-set reasoning, since it was ``already provable.''
But this heuristic prevented the conclusion from triggering further forward
chaining. This has been fixed. Thanks to Dave Greve for pointing out this
The fundamental utility that turns an
IF expression into a set of clauses
has been optimized to better handle tests of the form
(equal x 'constant)
and their negations. This eliminates an exponential explosion in large case
analyses. But it comes at the inconveience of sometimes reordering the
clauses produced. The latter aspect of this change may require you to change
some Subgoal numbers in proof hints. We apologize for the inconvenience.
Certification can now run faster (specifically, the compilation phase) for
books with very large structures generated by
make-event, when there is
significant sharing of substructure, because of a custom optimization of the
Lisp reader. Thanks to Sol Swords for bringing this efficiency issue to our
Jared Davis reported inefficiency in certain
make-event evaluation due
to a potentially expensive ``bad lisp object'' check on the expansion
produced by the
make-event. This check has been eliminated except in the
case that the expansion introduces packages (for example, by including a book
during the expansion phase that introduces packages). Thanks to Jared for
providing a helpful example.
The application of rules of class
induction had the potential to
loop (as commented in ACL2 source function
has been fixed. Thanks to Daron Vroon and Pete Manolios for sending nice
examples causing the loop.
Heuristics have been tweaked so that false goals may be simplified to
that had formerly been left unchanged by simplification, perhaps resulting in
useless and distracting proofs by induction. Thanks to Pete Manolios for
pointing out this issue by sending the following example:
(thm (<= (+ 1 (acl2-count x)) 0)). (Technical explanation: When every
literal in a clause simplifies to
nil, even though we might not normally
delete one or more such literals, we will replace the entire clause by the
Improved the efficiency of the built-in function,
take. Thanks to Bob
Boyer for suggesting this improvement.
ACL2 can now use evaluation to relieve hypotheses when applying
type-prescription rules. Thanks to Peter Dillinger and Dave Greve
for requesting this enhancement, and to Robert Krug for a relevant discussion
Evaluation has been sped up during theorems for calls of
avoiding repeated evaluation of the expression to which its variables are
bound. Thanks to Sol Swords for requesting this improvement and sending an
Modified a heuristic to avoid the opening up non-recursive function calls on
if-expressions. For example, the
thm form below is now admitted
(defun bar (x) (cons x x)) (thm (equal (bar (hide (if a b c))) (cons (hide (if a b c)) (hide (if a b c)))))
Fixed a soundness bug in destructor elimination, which was preventing some
cases from being generated. Thanks to Eric Smith for reporting this bug and
sending a helpful example. (Technical detail: the fixes were in ACL2 source
eliminate-destructors-clause1, and comments in the former contain Eric's
Fixed a bug that supported a proof of
nil by exploiting the fact that
portcullis commands were not included in check-sum computations in
a book's certificate. For such a proof of
nil, see the relevant
comment in the ACL2 source file
(deflabel note-4-0 ...).
Changed the implementation of
add-include-book-dir. The previous
implementation could allow relative pathnames to be stored in the
portcullis commands of certificates of books, which
perhaps could lead to unsoundness (though we did not try to exploit this to
nil). Thanks to Jared Davis for reporting a bug in our first new
implementation. An additional change to both
delete-include-book-dir is that these now work in raw-mode
(see set-raw-mode). (Thanks to Dave Greve for suggesting a reduction in the
warnings we produced related to raw-mode.) Note that it is no longer
permitted to make a direct call of the form
(table acl2-defaults-table :include-book-dir-alist ...); use
Fixed a soundness bug related to
defund-nx, have been provided for declaring
functions to be non-executable; see defun-nx. While we expect this bug to
occur only rarely if at all in practice, the following example shows how it
could be evoked.
;;;;;;;;;;;;;;;;;;;; ;;; Book sub.lisp ;;;;;;;;;;;;;;;;;;;; (in-package "ACL2") (defun f () (declare (xargs :guard t :non-executable t)) (mv-let (a b c) (mv 3 4) (declare (ignore a b)) c)) (defun g () (declare (xargs :guard t)) (prog2$ (mv-let (x y z) (mv 2 3 4) (declare (ignore x y z)) nil) (f))) (defthm g-nil (equal (g) nil) :hints (("Goal" :in-theory (disable (f)))) :rule-classes nil) ;;;;;;;;;;;;;;;;;;;; ;;; Book top.lisp ;;;;;;;;;;;;;;;;;;;; (in-package "ACL2") (include-book "sub") (defthm contradiction nil :hints (("Goal" :use g-nil)) :rule-classes nil)
The modification described above pertaining to
defun-nx also prevents
execution of non-executable functions that have been traced. The
following example illustrates the problem; now, the following
g is illegal, and the problem disappears if
defun-nx is used
(defun g (x) ; Use defun-nx to avoid an error after Version_3.6.1. (declare (xargs :guard t :non-executable t)) x) (g 3) ; causes error, as expected (trace$ g) (g 3) ; returned 3 before the bug fix; after fix, causes error as expected
A hard error was possible when attempting to include an uncertified book
containing events of the form
(make-event '(local ...)). This has
been fixed. Thanks to Sol Swords for bringing this issue to our attention.
Fixed a bug in the heuristic improvement described for Version_3.6 (see note-3-6) as ``We simplified induction schemes....'' The bug had prevented, in unusual cases such as the following (notice the impossible case), a proof by induction.
(defun foo (a x) (and (consp x) (case a (0 (foo (car x) (cdr x))) (1 (foo (cdr x) (car x))) (0 (foo a (cons x x)))))) (in-theory (disable (:type-prescription foo))) (thm (atom (foo a x)))
cw-gstack did not work with an
:evisc-tuple argument. This
has been fixed by changing
cw-gstack so that it now evaluates its
arguments. Thanks to Sol Swords for bringing this bug to our attention.
Fixed a bug in
pso during the printing of failure messages for
Fixed a bug in the handling of
#. (see sharp-dot-reader). Thanks to Bob
Boyer for bringing this bug to our attention.
Replaced a hard Lisp error with a clean error, in certain cases that a
hints value is erroneously supplied as a non-
(thm (equal x x) :hints 3).
Fixed a bug in the interaction of function tracing with conversion of a
logic mode. The following
example illustrates what had been wrong.
(defun f (x) (declare (xargs :mode :program)) (car x)) (f 3) ; raw Lisp hard error (trace$ f) (f 3) ; raw Lisp hard error (still) (defun f (x) (car x)) ; upgrade f to :logic mode (f 3) ; clean guard violation; f is no longer traced (trace$) ; uh oh - f is shown as traced (untrace$ f) (f 3) ; OUCH: hard Lisp error because old :program mode definition of ; the executable counterpart (sometimes called *1*f) was restored!
Made a fix so that when building ACL2 with `make' option
there will no longer be any safety-0 compiled code generated. Thanks to Gary
Byers for bringing this bug to our attention.
Fixed a bug in the handling of override-hints that generate custom
keyword hints (see custom-keyword-hints) involving the variable
stable-under-simplificationp. Thanks to Ian Johnson for bringing this
bug to our attention with explanation that included a helpful example,
included as comment in the ACL2 source code for function
saved_acl2 script in CLISP could contain unexpected characters where
simple newlines were expected. Dave Greve found this in a Cygwin environment
on Windows. Thanks to Dave for reporting this bug and experimenting with a
fix, and thanks to the CLISP folks for providing helpful information.
Fixed a bug that could make
oops cause an error. Also, the
oops command can no longer take you back before a
(GCL only) Fixed a bug that could occur when calling
trace in raw Lisp in
Proof summaries have been improved, so that they account for runes used in rewriting that takes place when generating goals to be proved in a forcing round. Thanks to Jared Davis for sending us an example illustrating this issue.
Fixed a bug that (at least in CCL) could put extra backslashes (`
a pathname that ACL2 writes out to the executable script created by a build.
Thanks to Gary Byers for explaining that the CCL behavior is legal (for our
previous use of Common Lisp function
We closed some holes in the handling of trust tags (also known as ``ttags'';
see defttag) by
include-book. The following example illustrates this
rather subtle situation. Consider the following book.
(in-package "ACL2") (make-event (er-progn (encapsulate () (defttag :foo) (value-triple "Imagine something bad here!")) (value '(value-triple :some-value))) :check-expansion t)Formerly, the following commands succeeded.
(certify-book "test3" 0 t :ttags :all) :u (include-book "test3" :ttags nil)But because of
:check-expansion t, we know that the event
(defttag :foo)is evaluated by the above
include-bookform, and hence the
include-book, above, should have specified
:foo. The problem was that
defttagforms evaluated during
make-eventexpansion did not contribute to the trust tag information stored in the book's certificate. Note: Because of this change, one should avoid using
:check-expansion twhen the expansion would introduce a
certify-booktime. For an example illustrating this issue, see make-event-details, specifically the new version of the section labeled ``A note on ttags'' at the end of that documentation topic.
Closed a small loophole that had the potential, in rare circumstances, to violate atomicity of under-the-hood updates for ACL2 arrays.
The following example was formerly allowed, but resulted in a guard-verified
g) whose guard proof obligation is not a theorem outside
encapsulate event. We now disallow guard verification for
functions introduced non-locally inside an
encapsulate event unless
we determine that the proof obligations hold outside the
event as well.
(encapsulate ((f (x) t)) (local (defun f (x) (declare (xargs :guard t)) (consp x))) ;; ERROR! (defun g (x) (declare (xargs :guard (f x))) (car x)))
The use of
comp on stobj functions had potentially caused a
hard Lisp error; for example, this could occur when
(defstobj foo fld)
was followed by
:comp foop. This has been fixed.
Fixed a bug that could cause a raw Lisp error when the first argument of
with-local-stobj is not a symbol.
It had been possible to use the reserved keyword :computed-hints-replacement as the name of a custom keyword hint (see custom-keyword-hints). This has been fixed. Thanks to Dave Greve, who pointed out a confusing hint error message (which has also been fixed) that led us to this issue.
Fixed a bug that could cause a hard Lisp error, instead of a graceful ACL2
error, if keyword
:backchain-limit-lst in a rule class is given a cons
that is not a true list, such as
(1 . 1).
Eliminated an error that could occur when redefining a function as a macro and then compiling, as in the example below.
(defun foo (x) x) :redef! (defmacro foo (x) x) :comp tThanks to Eric Smith for sending the above example in his bug report.
Fixed a bug that could result in an assertion when a clause-processor causes an error.
NEW AND UPDATED BOOKS AND RELATED INFRASTRUCTURE
See http://code.google.com/p/acl2-books/source/list for a record of books changed or added since the preceding release, with log entries.
We note in particular the new
system/ directory, which begins to specify
ACL2 system code in anticipation of opening the architecture of ACL2
(see defattach for a relevant tool). Some system functions were changed
slightly (but with the expectation of not generally affecting ACL2 behavior)
in support of the development of this directory. Those interested in
contributing to further such efforts are invited to contact the ACL2
New utilities have been provided for certifying most of the distributed books
with more `make'-level parallelism. For example, we have obtained close to
a 12x reduction in time by using `
make -j 24 regression-fast' on a
24-processor machine. For more information see
books/make-targets, or to
books/workshops in the regression run, see
books/regression-targets. Thanks to Sol Swords for providing these nice
The top-level makefile,
GNUmakefile, has been fixed so that the build
processes (which are inherently sequential) will ignore the
-j option of
`make'. Note that regressions can still, however, be done in parallel, as
-j option will be passed automatically to the appropriate `make'
The HONS version, supported primarily by Bob Boyer and Warren Hunt
(see hons-and-memoization), has undergone numerous improvements. For
example, keyword argument
:FORGET is now supported when calling
memoize from within the ACL2 loop, and system function
is memoized with the
:condition that both terms are function
applications (clearing the memo-table after each prover invocation). Thanks
to Jared Davis and Sol Swords for investigating the memoization of
worse-than, and with suitable
condition. Thanks also to Jared Davis
for contributing structural modifications to the implementation of
David Rager contributed modifications to the parallel version (see parallelism), which include taking advantage of atomic increments available at least since Version 1.0.21 of SBCL and Version 1.3 of CCL.