CERTIFY-BOOK

how to produce a certificate for a book
Major Section:  BOOKS

Examples:
(certify-book "my-arith")        ; certify in a world with 0 commands
(certify-book "my-arith" 3)      ; ... in a world with 3 commands
(certify-book "my-arith" ?)      ; ... in a world without checking the
                                   ;     number of commands
(certify-book "my-arith" 0 nil)  ; ... do not compile
(certify-book "my-arith" 0 t)    ; ... compile (default; see also below)
(certify-book "my-arith" 0 :all) ; ... compile exececutable counterparts
                                   ;     too (but see below)
(certify-book "my-arith" 0 t :ttags (foo))
                                   ; ... allow trust tag (ttag) foo
(certify-book "my-arith" 0 t :ttags :all)
                                   ; ... allow all trust tags (ttags)
(certify-book "my-arith" t)      ; certify from world of old certificate

General Form: (certify-book book-name k compile-flg :defaxioms-okp t/nil ; [default nil] :skip-proofs-okp t/nil ; [default nil] :save-expansion :save/t/nil ; [default nil] :ttags ttags ; [default nil] )

where book-name is a book name (see book-name), k is either t or an integer used to indicate your approval of the ``certification world.'' Compile-flg indicates whether you wish to compile the (functions in the) book. Compile-flg generally defaults to t, meaning to compile; nil means do not compile. However, if explicit compilation is suppressed then compile-flg is coerced to nil; see compilation.

The second argument k is optional as well; it defaults to 0.

Two keyword arguments, :defaxioms-okp and :skip-proofs-okp, determine how the system handles the inclusion of defaxiom events and skip-proofs events, respectively, in the book. The value t allows such events, but prints a warning message. The value nil is the default, and causes an error if such an event is found.

The keyword argument :ttags may normally be omitted. A few constructs, used for example if you are building your own system based on ACL2, may require it. See defttag for an explanation of this argument.

To advanced users only: in the rare case that you are willing to add to compilation time in return for compiling the executable counterparts of functions defined in the book, you may supply a value of :all for compile-flg. This setting is useful for compiling a book whose functions are called during macroexpansion, because evaluation during macroexpansion is done in a ``safe mode'' that avoids calling raw Lisp functions (see guards-and-evaluation).

The keyword argument :save-expansion controls whether or not a so-called ``book expansion'' file is written, obtained by appending the string "@expansion.lsp" to the end of the book name. See make-event for discussion of the book expansion; in a nutshell, make-event calls generate forms that replace them in the book expansion. Book expansion is skipped if compile-flg and :save-expansion are both nil. Otherwise, the values of nil and t for :save-expansion cause the book expansion to be created only when a make-event form occurs in a book (i.e., only if there is some expansion), or if at least one executable counterpart is to be compiled (see preceding paragraph). If the book expansion is created, then it is deleted after compilation if :save-expansion is nil. Finally, if :save-expansion is :save, then the book expansion file is created in all cases, and is not deleted.

For a general discussion of books, see books. Certify-book is akin to what we have historically called a ``proveall'': all the forms in the book are ``proved'' to guarantee their admissibility. More precisely, certify-book (1) reads the forms in the book, confirming that the appropriate packages are defined in the certification world; (2) does the full admissibility checks on each form (proving termination of recursive functions, proving theorems, etc.), checking as it goes that each form is an embedded event form (see embedded-event-form); (3) rolls the world back to the initial certification world and does an include-book of the book to check for local incompatibilities (see local-incompatibility); (4) writes a certificate recording not only that the book was certified but also recording the commands necessary to recreate the certification world (so the appropriate packages can be defined when the book is included in other worlds) and the check sums of all the books involved (see certificate); (5) compiles the book if so directed (and then loads the object file in that case). The result of executing a certify-book command is the creation of a single new event, which is actually an include-book event. If you don't want its included events in your present world, simply execute :ubt :here afterwards.

Certify-book requires that the default defun-mode (see default-defun-mode) be :logic when certification is attempted. If the mode is not :logic, an error is signalled.

An error will occur if certify-book has to deal with any uncertified book other than the one on which it was called. For example, if the book being certified includes another book, that subbook must already have been certified.

Certification occurs in some logical world, called the ``certification world.'' That world must contain the defpkgs needed to read and execute the forms in the book. The commands necessary to recreate that world from the ACL2 initial world will be copied into the certificate created for the book. Those commands will be re-executed whenever the book is included, to ensure that the appropriate packages (and all other names used in the certification world) are correctly defined. The certified book will be more often usable if the certification world is kept to a minimal extension of the ACL2 initial world. Thus, before you call certify-book for the first time on a book, you should get into the initial ACL2 world (e.g., with :ubt 1 or just starting a new version of ACL2), defpkg the desired packages, and then invoke certify-book.

The k argument to certify-book must be either a nonnegative integer or else one of the symbols t or ? in the ACL2 package. If k is an integer, then it must be the number of commands that have been executed after the initial ACL2 world to create the world in which certify-book was called. One way to obtain this number is by doing :pbt :start to see all the commands back to the first one.

If k is t it means that certify-book should use the same world used in the last certification of this book. K may be t only if you call certify-book in the initial ACL2 world and there is a certificate on file for the book being certified. (Of course, the certificate is probably invalid.) In this case, certify-book reads the old certificate to obtain the portcullis commands and executes them to recreate the certification world.

Finally, k may be ?, in which case there is no check made on the certification world. That is, if k is ? then no action related to the preceding two paragraphs is performed, which can be a nice convenience but at the cost of eliminating a potentially valuable check that the certification world may be as expected.

If you have a certified book that has remained unchanged for some time you are unlikely even to remember the appropriate defpkgs for it. If you begin to change the book, don't throw away its certificate file just because it has become invalid! It is an important historical document until the book is re-certified.

When certify-book is directed to produce a compiled file, it calls the Common Lisp function compile-file on the original source file. This creates a compiled file with an extension known to ACL2, e.g., if the book is named "my-book" then the source file is "my-book.lisp" and the compiled file under GCL will be "my-book.o" while under SBCL it will be "my-book.fasl". The compiled file is then loaded. When include-book is used later on "my-book" it will automatically load the compiled file, provided the compiled file has a later write date than the source file. The only effect of such compilation and loading is that the functions defined in the book execute faster. See guard for a discussion of the issues.

When certify-book is directed not to produce a compiled file, it will delete any existing compiled file for the book, so as not to mislead include-book into loading the now outdated compiled file.

After execution of a certify-book form, the value of acl2-defaults-table is restored to what it was immediately before that certify-book form was executed. See acl2-defaults-table.

This completes the tour through the documentation of books.