Re: GNU Guile 2.9.9 Released [beta]

[Zelphir Kaltstahl]

I am already super excited about Guile 3.0.0 and JIT.

I've not had to complain about Guile's speed so far and there are
low-level things like using integers as bits to enable high performance
things, but hey, if simply by upgrading to a new version most Guile
programs run faster, that's great!

I've also steadily discovered new corners of the language as in: "Oh
there already is a library for that!" (for example fibers library or
futures and parallel forms) or "Oh wow, I can go so low-level with that
and still have high level language features and abstractions!" (for
example with using integers as bits, for my attempt of writing a chess
engine) or "Ah, that's how I should use it!" (for example with R6RS
exception handling (conditions)). So I am looking forward to learning
more about Guile and see it being used in more scenarios in the future.

Thanks for keeping up the good work and thanks for everyone contributing
to the Guile ecosystem,
Zelphir

On 1/13/20 9:39 AM, Andy Wingo wrote:
> We are pleased to announce GNU Guile release 2.9.9.  This is the ninfth
> and probably final pre-release of what will eventually become the 3.0
> release series.
>
> Compared to the current stable series (2.2.x), the future Guile 3.0 adds
> support for just-in-time native code generation, speeding up all Guile
> programs.  See the NEWS extract at the end of the mail for full details.
>
> Compared to the previous prerelease (2.9.7), Guile 2.9.8 fixes a number
> of bugs.
>
> The current plan is to make a 3.0.0 final release on 17 January 2020.
> If there's nothing wrong with this prerelease, 3.0.0 will be essentially
> identical to 2.9.9.  With that in mind, please test and make sure the
> release works on your platform!  Please send any build reports (success
> or failure) to address@hidden, along with platform details.  You
> can file a bug by sending mail to address@hidden.
>
> The Guile web page is located at http://gnu.org/software/guile/, and
> among other things, it contains a copy of the Guile manual and pointers
> to more resources.
>
> Guile is an implementation of the Scheme programming language, packaged
> for use in a wide variety of environments.  In addition to implementing
> the R5RS, R6RS, and R7RS Scheme standards, Guile includes a module
> system, full access to POSIX system calls, networking support, multiple
> threads, dynamic linking, a foreign function call interface, powerful
> string processing, and HTTP client and server implementations.
>
> Guile can run interactively, as a script interpreter, and as a Scheme
> compiler to VM bytecode.  It is also packaged as a library so that
> applications can easily incorporate a complete Scheme interpreter/VM.
> An application can use Guile as an extension language, a clean and
> powerful configuration language, or as multi-purpose "glue" to connect
> primitives provided by the application.  It is easy to call Scheme code
> From C code and vice versa.  Applications can add new functions, data
> types, control structures, and even syntax to Guile, to create a
> domain-specific language tailored to the task at hand.
>
> Guile 2.9.9 can be installed in parallel with Guile 2.2.x; see
> http://www.gnu.org/software/guile/manual/html_node/Parallel-Installations.html.
>
> A more detailed NEWS summary follows these details on how to get the
> Guile sources.
>
> Here are the compressed sources:
>   http://alpha.gnu.org/gnu/guile/guile-2.9.9.tar.lz   (10MB)
>   http://alpha.gnu.org/gnu/guile/guile-2.9.9.tar.xz   (12MB)
>   http://alpha.gnu.org/gnu/guile/guile-2.9.9.tar.gz   (21MB)
>
> Here are the GPG detached signatures[*]:
>   http://alpha.gnu.org/gnu/guile/guile-2.9.9.tar.lz.sig
>   http://alpha.gnu.org/gnu/guile/guile-2.9.9.tar.xz.sig
>   http://alpha.gnu.org/gnu/guile/guile-2.9.9.tar.gz.sig
>
> Use a mirror for higher download bandwidth:
>   http://www.gnu.org/order/ftp.html
>
> Here are the SHA256 checksums:
>
>   59f136e5db36eba070cc5e68784e632dc2beae4b21fd6c7c8ed2c598cc992efc  
> guile-2.9.9.tar.lz
>   bf71920cfa23e59fc6257bee84ef4dfeccf4f03e96bb8205592e09f9dbff2969  
> guile-2.9.9.tar.xz
>   eafe394cf99d9dd1ab837e6d1b9b2b8d9f0cd13bc34e64ca92456ce1bc2b1925  
> guile-2.9.9.tar.gz
>
> [*] Use a .sig file to verify that the corresponding file (without the
> .sig suffix) is intact.  First, be sure to download both the .sig file
> and the corresponding tarball.  Then, run a command like this:
>
>   gpg --verify guile-2.9.9.tar.gz.sig
>
> If that command fails because you don't have the required public key,
> then run this command to import it:
>
>   gpg --keyserver keys.gnupg.net --recv-keys 
> 4FD4D288D445934E0A14F9A5A8803732E4436885
>
> and rerun the 'gpg --verify' command.
>
> This release was bootstrapped with the following tools:
>   Autoconf 2.69
>   Automake 1.16.1
>   Libtool 2.4.6
>   Gnulib v0.1-1157-gb03f418
>   Makeinfo 6.7
>
> An extract from NEWS follows.
>
>
> Changes since alpha 2.9.8 (since 2.9.7):
>
> * Notable changes
>
> ** `define-module' #:autoload no longer pulls in the whole module
>
> One of the ways that a module can use another is "autoloads".  For
> example:
>
>   (define-module (a) #:autoload (b) (make-b))
>
> In this example, module `(b)' will only be imported when the `make-b'
> identifier is referenced.  However besides the imprecision about when a
> given binding is actually referenced, this mechanism used to cause the
> whole imported module to become available, not just the specified
> bindings.  This has now been changed to only import the specified bindings.
>
> This is a backward-incompatible change.  The fix is to mention all
> bindings of interest in the autoload clause.  Feedback is welcome.
>
> ** `guard' no longer unwinds the stack for clause tests
>
> SRFI-34, and then R6RS and R7RS, defines a `guard' form that is a
> shorthand for `with-exception-handler'.  The cond-like clauses for the
> exception handling are specified to run with the continuation of the
> `guard', while any re-propagation of the exception happens with the
> continuation of the original `raise'.
>
> In practice, this means that one needs full `call-with-continuation' to
> implement the specified semantics, to be able to unwind the stack to the
> cond clauses, then rewind if none match.  This is not only quite
> expensive, it is also error-prone as one usually doesn't want to rewind
> dynamic-wind guards in an exceptional situation.  Additionally, as
> continuations bind tightly to the current thread, it makes it impossible
> to migrate a subcomputation with a different thread if a `guard' is live
> on the stack, as is done in Fibers.
>
> Guile now works around these issues by running the test portion of the
> guard expressions within the original `raise' continuation, and only
> unwinding once a test matches.  This is an incompatible semantic change
> but we think the situation is globally much better, and we expect that
> very few people will be affected by the change.
>
> ** Improve SRFI-43 vector-fill!
>
> SRFI-43 vector-fill! now has the same performance whether an optional
> range is provided or not, and is also provided in core.  As a side
> effect, vector-fill! and vector_fill_x no longer work on non-vector
> rank-1 arrays.  Such cases were handled incorrectly before; for example,
> prior to this change:
>
>   (define a (make-vector 10 'x))
>   (define b (make-shared-array a (lambda (i) (list (* 2 i))) 5))
>   (vector-fill! b 'y)
>
>   => #1(y y y x x)
>
> This is now an error.  Instead, use array-fill!.
>
> ** Fix compilation on 32-bit targets
>
> A compile error introduced in 2.9.3 prevented compilation on 32-bit
> targets.  This has been fixed.
>
> ** Fix a bug in closure conversion
>
> Thanks for Stefan Israelsson Tampe for the report.
>
> ** Fix omission in R7RS support
>
> Somewhat embarrassingly, the R7RS support added earlier in 2.9 failed to
> include an implementation of `define-library'.  This oversight has been
> corrected :)
>
> ** Optionally allow duplicate field names in core records
>
> See the new #:allow-duplicate-field-names? keyword argument to
> `make-record-type' in the manual, for more.  This restores a needed
> feature to R6RS records.
>
> ** Fix default value of thread-local fluids
>
> Before, `fluid-ref' on an unbound thread-local fluid was returning #f
> instead of the default value of the fluid.  Thanks to Rob Browning for
> the fix!
>
>
> 
> Changes in alpha 2.9.x (since the stable 2.2 series):
>
> * Notable changes
>
> ** Just-in-time code generation
>
> Guile programs now run up to 4 times faster, relative to Guile 2.2,
> thanks to just-in-time (JIT) native code generation.  Notably, this
> brings the performance of "eval" as written in Scheme back to the level
> of "eval" written in C, as in the days of Guile 1.8.
>
> See "Just-In-Time Native Code" in the manual, for more information.  JIT
> compilation will be enabled automatically and transparently.  To disable
> JIT compilation, configure Guile with `--enable-jit=no' or
> `--disable-jit'.  The default is `--enable-jit=auto', which enables the
> JIT if it is available.  See `./configure --help' for more.
>
> JIT compilation is enabled by default on x86-64, i686, ARMv7, and
> AArch64 targets.
>
> ** Lower-level bytecode
>
> Relative to the virtual machine in Guile 2.2, Guile's VM instruction set
> is now more low-level.  This allows it to express more advanced
> optimizations, for example type check elision or integer
> devirtualization, and makes the task of JIT code generation easier.
>
> Note that this change can mean that for a given function, the
> corresponding number of instructions in Guile 3.0 may be higher than
> Guile 2.2, which can lead to slowdowns when the function is interpreted.
> We hope that JIT compilation more than makes up for this slight
> slowdown.
>
> ** Interleaved internal definitions and expressions allowed
>
> It used to be that internal definitions had to precede all expressions
> in their bodies.  This restriction has been relaxed.  If an expression
> precedes an internal definition, it is treated as if it were a
> definition of an unreferenced variable.  For example, the expression
> `(foo)' transforms to the equivalent of `(define _ (begin (foo) #f))',
> if it precedes other definitions.
>
> This change improves the readability of Guile programs, as it used to be
> that program indentation tended to increase needlessly to allow nested
> `let' and `letrec' to re-establish definition contexts after initial
> expressions, for example for type-checks on procedure arguments.
>
> ** Record unification
>
> Guile used to have a number of implementations of structured data types
> in the form of "records": a core facility, SRFI-9 (records), SRFI-35
> (condition types -- a form of records) and R6RS records.  These
> facilities were not compatible, as they all were built in different
> ways.  This had the unfortunate corollary that SRFI-35 conditions were
> not compatible with R6RS conditions.  To fix this problem, we have now
> added the union of functionality from all of these record types into
> core records: single-inheritance subtyping, mutable and immutable
> fields, and so on.  See "Records" in the manual, for full details.
>
> R6RS records, SRFI-9 records, and the SRFI-35 and R6RS exception types
> have been accordingly "rebased" on top of core records.
>
> ** Reimplementation of exceptions
>
> Since Guile's origins 25 years ago, `throw' and `catch' have been the
> primary exception-handling primitives.  However these primitives have
> two problems.  One is that it's hard to handle exceptions in a
> structured way using `catch'.  Few people remember what the
> corresponding `key' and `args' are that an exception handler would see
> in response to a call to `error', for example.  In practice, this
> results in more generic catch-all exception handling than one might
> like.
>
> The other problem is that `throw', `catch', and especially
> `with-throw-handler' are quite unlike what the rest of the Scheme world
> uses.  R6RS and R7RS, for example, have mostly converged on
> SRFI-34-style `with-exception-handler' and `raise' primitives, and
> encourage the use of SRFI-35-style structured exception objects to
> describe the error.  Guile's R6RS layer incorporates an adapter between
> `throw'/`catch' and structured exception handling, but it didn't apply
> to SRFI-34/SRFI-35, and we would have to duplicate it for R7RS.
>
> In light of these considerations, Guile has now changed to make
> `with-exception-handler' and `raise-exception' its primitives for
> exception handling and defined a hierarchy of R6RS-style exception types
> in its core.  SRFI-34/35, R6RS, and the exception-handling components of
> SRFI-18 (threads) have been re-implemented in terms of this core
> functionality.  There is also a a compatibility layer that makes it so
> that exceptions originating in `throw' can be handled by
> `with-exception-hander', and vice-versa for `raise-exception' and
> `catch'.
>
> Generally speaking, users will see no difference.  The one significant
> difference is that users of SRFI-34 will see more exceptions flowing
> through their `with-exception-handler'/`guard' forms, because whereas
> before they would only see exceptions thrown by SRFI-34, now they will
> see exceptions thrown by R6RS, R7RS, or indeed `throw'.
>
> Guile's situation is transitional.  Most exceptions are still signalled
> via `throw'.  These will probably migrate over time to
> `raise-exception', while preserving compatibility of course.
>
> See "Exceptions" in the manual, for full details on the new API.
>
> ** Optimization of top-level bindings within a compilation unit
>
> At optimization level 2 and above, Guile's compiler is now allowed to
> inline top-level definitions within a compilation unit.  See
> "Declarative Modules" in the manual, for full details.  This change can
> improve the performance of programs with many small top-level
> definitions by quite a bit!
>
> At optimization level 3 and above, Guile will assume that any top-level
> binding in a declarative compilation unit that isn't exported from a
> module can be completely inlined into its uses.  (Prior to this change,
> -O3 was the same as -O2.)  Note that with this new
> `seal-private-bindings' pass, private declarative bindings are no longer
> available for access from the first-class module reflection API.  The
> optimizations afforded by this pass can be useful when you need a speed
> boost, but having them enabled at optimization level 3 means they are
> not on by default, as they change Guile's behavior in ways that users
> might not expect.
>
> ** By default, GOOPS classes are not redefinable
>
> It used to be that all GOOPS classes were redefinable, at least in
> theory.  This facility was supported by an indirection in all "struct"
> instances, even though only a subset of structs would need redefinition.
> We wanted to remove this indirection, in order to speed up Guile
> records, allow immutable Guile records to eventually be described by
> classes, and allow for some optimizations in core GOOPS classes that
> shouldn't be redefined anyway.
>
> Thus in GOOPS now there are classes that are redefinable and classes
> that aren't.  By default, classes created with GOOPS are not
> redefinable.  To make a class redefinable, it should be an instance of
> `<redefinable-class>'.  See "Redefining a Class" in the manual for more
> information.
>
> ** Define top-level bindings for aux syntax: `else', `=>', `...', `_'
>
> These auxiliary syntax definitions are specified to be defined in the
> R6RS and the R7RS.  They were previously unbound, even in the R6RS
> modules.  This change is not anticipated to cause any incompatibility
> with existing Guile code, and improves things for R6RS and R7RS users.
>
> ** Conventional gettext alias is now `G_'
>
> Related to the last point, since the "Fix literal matching for
> module-bound literals" change in the 2.2 series, it was no longer
> possible to use the conventional `_' binding as an alias for `gettext',
> because a local `_' definition would prevent `_' from being recognized
> as auxiliary syntax for `match', `syntax-rules', and similar.  The new
> recommended conventional alias for `gettext' is `G_'.
>
> ** Add --r6rs command-line option
>
> The new `install-r6rs!' procedure adapts Guile's defaults to be more
> R6RS-compatible.  This procedure is called if the user passes `--r6rs'
> as a command-line argument.  See "R6RS Incompatibilities" in the manual,
> for full details.
>
> ** Add support for R7RS
>
> Thanks to Göran Weinholt and OKUMURA Yuki, Guile now implements the R7RS
> modules.  As the R7RS library syntax is a subset of R6RS, to use R7RS
> you just `(import (scheme base))' and off you go.  As with R6RS also,
> there are some small lexical incompatibilities regarding hex escapes;
> see "R6RS Support" in the manual, for full details.
>
> Also as with R6RS, there is an `install-r7rs!' procedure and a `--r7rs'
> command-line option.
>
> ** Add #:re-export-and-replace argument to `define-module'
>
> This new keyword specifies a set of bindings to re-export, but also
> marks them as intended to replace core bindings.  See "Creating Guile
> Modules" in the manual, for full details.
>
> Note to make this change, we had to change the way replacement flags are
> stored, to being associated with modules instead of individual variable
> objects.  This means that users who #:re-export an imported binding that
> was already marked as #:replace by another module will now see warnings,
> as they need to use #:re-export-and-replace instead.
>
> ** `iota' in core and SRFI-1 `iota' are the same
>
> Previously, `iota' in core would not accept start and step arguments and
> would return an empty list for negative count. Now there is only one
> `iota' function with the extended semantics of SRFI-1.  Note that as an
> incompatible change, core `iota' no longer accepts a negative count.
>
> * New deprecations
>
> ** scm_t_uint8, etc deprecated in favor of C99 stdint.h
>
> It used to be that Guile defined its own `scm_t_uint8' because C99
> `uint8_t' wasn't widely enough available.  Now Guile finally made the
> change to use C99 types, both internally and in Guile's public headers.
>
> Note that this also applies to SCM_T_UINT8_MAX, SCM_T_INT8_MIN, for intN
> and uintN for N in 8, 16, 32, and 64.  Guile also now uses ptrdiff_t
> instead of scm_t_ptrdiff, and similarly for intmax_t, uintmax_t,
> intptr_t, and uintptr_t.
>
> ** The two-argument form of `record-constructor'
>
> Calling `record-constructor' with two arguments (the record type and a
> list of field names) is deprecated.  Instead, call with just one
> argument, and provide a wrapper around that constructor if needed.
>
> * Incompatible changes
>
> ** All deprecated code removed
>
> All code deprecated in Guile 2.2 has been removed.  See older NEWS, and
> check that your programs can compile without linker warnings and run
> without runtime warnings.  See "Deprecation" in the manual.
>
> In particular, the function `scm_generalized_vector_get_handle' which
> was deprecated in 2.0.9 but remained in 2.2, has now finally been
> removed. As a replacement, use `scm_array_get_handle' to get a handle
> and `scm_array_handle_rank' to check the rank.
>
> ** Remove "self" field from vtables and "redefined" field from classes
>
> These fields were used as part of the machinery for class redefinition
> and is no longer needed.
>
> ** VM hook manipulation simplified
>
> The low-level mechanism to instrument a running virtual machine for
> debugging and tracing has been simplified.  See "VM Hooks" in the
> manual, for more.
>
> * Changes to the distribution
>
> ** New effective version
>
> The "effective version" of Guile is now 3.0, which allows parallel
> installation with other effective versions (for example, the older Guile
> 2.2).  See "Parallel Installations" in the manual for full details.
> Notably, the `pkg-config' file is now `guile-3.0', and there are new
> `guile-3' and `guile-3.0' features for `cond-expand'.
>