From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Andy Wingo Newsgroups: gmane.lisp.guile.devel Subject: ongoing NEWS Date: Thu, 18 Jun 2009 22:14:44 +0200 Message-ID: NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1245356095 3721 80.91.229.12 (18 Jun 2009 20:14:55 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 18 Jun 2009 20:14:55 +0000 (UTC) To: guile-devel Original-X-From: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Thu Jun 18 22:14:52 2009 Return-path: Envelope-to: guile-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MHO0T-0003Hy-Aj for guile-devel@m.gmane.org; Thu, 18 Jun 2009 22:14:46 +0200 Original-Received: from localhost ([127.0.0.1]:54444 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MHO0S-0000hU-M8 for guile-devel@m.gmane.org; Thu, 18 Jun 2009 16:14:44 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MHO0M-0000gL-M4 for guile-devel@gnu.org; Thu, 18 Jun 2009 16:14:38 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MHO0H-0000Td-5R for guile-devel@gnu.org; Thu, 18 Jun 2009 16:14:38 -0400 Original-Received: from [199.232.76.173] (port=33231 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MHO0H-0000TO-0r for guile-devel@gnu.org; Thu, 18 Jun 2009 16:14:33 -0400 Original-Received: from a-sasl-quonix.sasl.smtp.pobox.com ([208.72.237.25]:63842 helo=sasl.smtp.pobox.com) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MHO0G-0007eR-Hv for guile-devel@gnu.org; Thu, 18 Jun 2009 16:14:32 -0400 Original-Received: from localhost.localdomain (unknown [127.0.0.1]) by a-sasl-quonix.sasl.smtp.pobox.com (Postfix) with ESMTP id 4FF731FCF1 for ; Thu, 18 Jun 2009 16:14:31 -0400 (EDT) Original-Received: from unquote (unknown [82.123.244.190]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by a-sasl-quonix.sasl.smtp.pobox.com (Postfix) with ESMTPSA id 7DDAA1FCEF for ; Thu, 18 Jun 2009 16:14:30 -0400 (EDT) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.92 (gnu/linux) X-Pobox-Relay-ID: A2007C60-5C44-11DE-8378-B5D1A546830D-02397024!a-sasl-quonix.pobox.com X-detected-operating-system: by monty-python.gnu.org: Solaris 10 (beta) X-BeenThere: guile-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Developers list for Guile, the GNU extensibility library" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Errors-To: guile-devel-bounces+guile-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.lisp.guile.devel:8697 Archived-At: Hey, Not yet done with my part of the NEWS, though I hope to finish by noon or so tomorrow. But here is some of what I have, for review: ** The stack limit is now initialized from the environment. If getrlimit(2) is available and a stack limit is set, Guile will set its stack limit to 80% of the rlimit. Otherwise the limit is 160000 words, a four-fold increase from the earlier default limit. ** Fix bad interaction between `false-if-exception' and stack-call. Exceptions thrown by `false-if-exception' were erronously causing the stack to be saved, causing later errors to show the incorrectly-saved backtrace. This has been fixed. ** Files loaded with primitive-load-path will now be compiled automatically. If a compiled .go file corresponding to a .scm file is not found or is not fresh, the .scm file will be compiled on the fly, and the resulting .go file stored away. An advisory note will be printed on the console. Note that this mechanism depends on preservation of the .scm and .go modification times; if the .scm or .go files are moved after installation, care should be taken to preserve their original timestamps. Autocompiled files will be stored in the user's ~/.guile-ccache directory, which will be created if needed. This is analogous to ccache's behavior for C files. To inhibit autocompilation, set the GUILE_AUTO_COMPILE environment variable to 0, or pass --no-autocompile on the Guile command line. ** New environment variables: GUILE_LOAD_COMPILED_PATH, GUILE_SYSTEM_LOAD_COMPILED_PATH GUILE_LOAD_COMPILED_PATH is for compiled files what GUILE_LOAD_PATH is for source files. It is a different path, however, because compiled files are architecture-specific. GUILE_SYSTEM_LOAD_COMPILED_PATH is like GUILE_SYSTEM_PATH. ** New global variables: %load-compiled-path, %load-compiled-extensions These are analogous to %load-path and %load-extensions. ** New installation directory: $(pkglibdir)/1.9/ccache If $(libdir) is /usr/lib, for example, Guile will install its .go files to /usr/lib/guile/1.9/ccache. These files are architecture-specific. ** scm_primitive_load_path has additional argument, exception_on_error ** scm_stat has additional argument, exception_on_error ** New entry into %guile-build-info: `ccachedir' Probably should be removed? ** New reader macros: #' #` #, #,@ These macros translate, respectively, to `syntax', `quasisyntax', `unsyntax', and `unsyntax-splicing'. See the R6RS for more information. These reader macros may be overridden by `read-hash-extend'. ** Incompatible change to #' Guile did have a #' hash-extension, by default, which just returned the subsequent datum: #'foo => foo. In the unlikely event that anyone actually used this, this behavior may be reinstated via the `read-hash-extend' mechanism. ** Scheme expresssions may be commented out with #; #; comments out an entire expression. See the R6RS for more information. ** make-stack with a tail-called procedural narrowing argument no longer works (with compiled procedures) It used to be the case that a captured stack could be narrowed to select calls only up to or from a certain procedure, even if that procedure already tail-called another procedure. This was because the debug information from the original procedure was kept on the stack. Now with the new compiler, the stack only contains active frames from the current continuation. A narrow to a procedure that is not in the stack will result in an empty stack. To fix this, narrow to a procedure that is active in the current continuation, or narrow to a specific number of stack frames. ** backtraces through compiled procedures only show procedures that are active in the current continuation Similarly to the previous issue, backtraces in compiled code may be different from backtraces in interpreted code. There are no semantic differences, however. Please mail bug-guile@gnu.org if you see any deficiencies with Guile's backtraces. ** syntax-rules and syntax-case macros now propagate source information through to the expanded code This should result in better backtraces. ** The currying behavior of `define' has been removed. Before, `(define ((f a) b) (* a b))' would translate to (define f (lambda (a) (lambda (b) (* a b)))) Now a syntax error is signalled, as this syntax is not supported by default. If there is sufficient demand, this syntax can be supported again by default. ** All modules have names now Before, you could have anonymous modules: modules without names. Now, because of hygiene and macros, all modules have names. If a module was created without a name, the first time `module-name' is called on it, a fresh name will be lazily generated for it. ** Many syntax errors have different texts now Syntax errors still throw to the `syntax-error' key, but the arguments are often different now. Perhaps in the future, Guile will switch to using standard srfi-35 conditions. ** Returning multiple values to compiled code will silently truncate the values to the expected number For example, the interpreter would raise an error evaluating the form, `(+ (values 1 2) (values 3 4))', because it would see the operands as being two compound "values" objects, to which `+' does not apply. The compiler, on the other hand, receives multiple values on the stack, not as a compound object. Given that it must check the number of values anyway, if too many values are provided for a continuation, it chooses to truncate those values, effectively evaluating `(+ 1 3)' instead. The idea is that the semantics that the compiler implements is more intuitive, and the use of the interpreter will fade out with time. This behavior is allowed both by the R5RS and the R6RS. ** Multiple values in compiled code are not represented by compound objects This change may manifest itself in the following situation: (let ((val (foo))) (do-something) val) In the interpreter, if `foo' returns multiple values, multiple values are produced from the `let' expression. In the compiler, those values are truncated to the first value, and that first value is returned. In the compiler, if `foo' returns no values, an error will be raised, while the interpreter would proceed. Both of these behaviors are allowed by R5RS and R6RS. The compiler's behavior is more correct, however. If you wish to preserve a potentially multiply-valued return, you will need to set up a multiple-value continuation, using `call-with-values'. ** Defmacros are now implemented in terms of syntax-case. The practical ramification of this is that the `defmacro?' predicate has been removed, along with `defmacro-transformer', `macro-table', `xformer-table', `assert-defmacro?!', `set-defmacro-transformer!' and `defmacro:transformer'. This is because defmacros are simply macros. If any of these procedures provided useful facilities to you, we encourage you to contact the Guile developers. ** psyntax is now the default expander Scheme code is now expanded by default by the psyntax hygienic macro expander. Expansion is performed completely before compilation or interpretation. Notably, syntax errors will be signalled before interpretation begins. In the past, many syntax errors were only detected at runtime if the code in question was memoized. As part of its expansion, psyntax renames all lexically-bound identifiers. Original identifier names are preserved and given to the compiler, but the interpreter will see the renamed variables, e.g., `x432' instead of `x'. Note that the psyntax that Guile uses is a fork, as Guile already had modules before incompatible modules were added to psyntax -- about 10 years ago! Thus there are surely a number of bugs that have been fixed in psyntax since then. If you find one, please notify bug-guile@gnu.org. ** syntax-rules and syntax-case are available by default. There is no longer any need to import the `(ice-9 syncase)' module (which is now deprecated). The expander may be invoked directly via `sc-expand', though it is normally searched for via the current module transformer. Also, the helper routines for syntax-case are available in the default environment as well: `syntax->datum', `datum->syntax', `bound-identifier=?', `free-identifier=?', `generate-temporaries', `identifier?', and `syntax-violation'. See the R6RS for documentation. ** Lexical bindings introduced by hygienic macros may not be referenced by nonhygienic macros. If a lexical binding is introduced by a hygienic macro, it may not be referenced by a nonhygienic macro. For example, this works: (let () (define-macro (bind-x val body) `(let ((x ,val)) ,body)) (define-macro (ref x) x) (bind-x 10 (ref x))) But this does not: (let () (define-syntax bind-x (syntax-rules () ((_ val body) (let ((x val)) body)))) (define-macro (ref x) x) (bind-x 10 (ref x))) It is not normal to run into this situation with existing code. However, as code is ported over from defmacros to syntax-case, it is possible to run into situations like this. In the future, Guile will probably port its `while' macro to syntax-case, which makes this issue one to know about. ** Macros may no longer be referenced as first-class values. In the past, you could evaluate e.g. `if', and get its macro value. Now, expanding this form raises a syntax error. Macros still /exist/ as first-class values, but they must be /referenced/ via the module system, e.g. `(module-ref (current-module) 'if)'. This decision may be revisited before the 2.0 release. Feedback welcome to guile-devel@gnu.org (subscription required) or bug-guile@gnu.org (no subscription required). ** New macro type: syncase-macro XXX Need to decide whether to document this for 2.0, probably should: make-syncase-macro, make-extended-syncase-macro, macro-type, syncase-macro-type, syncase-macro-binding ** `(ice-9 syncase)' has been deprecated. As syntax-case is available by default, importing `(ice-9 syncase)' has no effect, and will trigger a deprecation warning. ** Fix bug in `module-bound?'. `module-bound?' was returning true if a module did have a local variable, but one that was unbound, but another imported module bound the variable. This was an error, and was fixed. ** BUG: Automatic compilation will be attempted when it shouldn't. For example, the old (lang elisp) modules are meant to be interpreted, not compiled. This bug will be fixed before 2.0. Andy -- http://wingolog.org/