guile-3.0.10

[Bruce Dubbs]

New point version.

[Bruce Dubbs]

Changes in 3.0.10 (since 3.0.9)

• Notable changes

Beginnings of support for alternate back-ends

A number of adaptations and additions of as-yet unstable interfaces have been made to allow third-party projects such as the Hoot Guile-to-WebAssembly whole-program compiler (​https://spritely.institute/hoot/) to use the Guile front-end and optimizer. Depending on how Hoot development goes, we may consider adding first-class support for WebAssembly as a compilation target; discussion is welcome on the guile-devel mailing list.

define in all bodies

define adds a definition to the body in which it appears, as if each non-tail definition or expression in that body were a binding in a surrounding letrec* clause. However, in some places, using define would result in the annoying error "definition in expression context, where definitions are not allowed", which could be fixed by explicitly adding a surrounding binding contour, for example an empty let. This was because there was no implicit surrounding lexical binding contour for the body of when and unless, for cond clauses, case clauses, and-let* bodies, and with-fluids. But no more; now these contexts now create a binding contour, allowing the use of define.

Two bug fixes of note regarding scoping of top-level variables

Previously, a reference to a top-level variable in a module other than the current module would be silently rewritten to reference the current module, if the variable was unbound in its original module. This was a hack from the early days of when we extended psyntax to know about the module system, and is now fixed to properly use the scope of the introduced binding instead of the scope of the macro use site.

Also, embarrassingly, sometimes macro-introduced top-level variables would use the same generated name. This is because of the strategy discussed in the manual, "Hygiene and the Top-Level"; sometimes the hashes would collide, for example if two definitions were the same in the beginning and only differed long into the end. This has been fixed to ensure name uniqueness.

• New interfaces and functionality

R6RS custom textual ports

Guile finally supports this venerable R6RS interface; see "Custom Ports" in the manual for more. These ports are suspendable (see "Non-Blocking I/O"). Also new in this release, custom binary ports are now suspendable as well.

New "soft port" interface

Instead of using R6RS custom textual ports, we recommend the new "soft ports" facility, because it is easier to use while also being more expressive. See "Soft Ports" in the manual for more details.

Soft ports are implemented by the new module (ice-9 soft-ports). There is a legacy "soft ports" facility exported by (guile) which will be deprecated at some point.

New "custom port" facility: (ice-9 custom-ports)

Custom ports are like R6RS custom binary ports, but lower-level, having access to all of Guile's internal port API. See "Custom Ports" in the manual.

New surface syntax: Wisp (SRFI-119)

Guile now includes SRFI-119, commonly referred to as Wisp (for "Whitespace for Lisp"), a Pythonesque surface syntax for Scheme where parentheses are replaced by equivalent indentation. See SRFI-119 in the manual.

New warning: unused-module

This analysis, enabled at `-W2', issues warnings for modules that appear in a use-modules' form or as a #:use-module clause of define-module', and whose bindings are unused. This is useful to trim the list of imports of a module.

In some cases, the compiler cannot conclude whether a module is definitely unused---this is notably the case for modules that are only used at macro-expansion time, such as (srfi srfi-26). In those cases, the compiler reports it as "possibly unused".

New documentation on inline procedure property declarations

Did you know that you can annotate procedures with properties? It goes like this:

  (define (frobnicate)
    #((fruits . (apple banana)))
    (whatever))
  (procedure-property frobnicate 'fruits) => (apple banana)

Now you know, and now it is documented in "Procedure Properties" in the manual. It has been this way since at Guile 2.0, but was never documented before.

New procedure annotation: maybe-unused

The utility of the -Wunused-toplevel warning, enabled at -W2, has historically been somewhat limited, especially when a macro generates a number of bindings, not all of which may be used. To produce more useful results, we now allow procedures to set the maybe-unused property, which if true will not result in unused-toplevel warnings. This property is set by define-inlinable, in case an inline binding never needs the procedure-as-value definition.

New exports from (system foreign): read-c-struct, write-c-struct

See "Foreign Structs" in the manual. These macros are like the older parse-c-struct / make-c-struct procedures, but they are more efficient because they inline the field accesses and don't deal in lists. Wider backtraces when not writing to a terminal

When writing a backtrace, if the output port is not a terminal, Guile truncates the lines at 500 characters instead of 80. Override this width via the default-frame-width parameter exported by the `(system repl debug)` module.

copy-file now supports copy-on-write

The copy-file procedure now takes an additional keyword argument, #:copy-on-write, specifying whether copy-on-write should be done, if the underlying file-system supports it. Possible values are 'always, 'auto and 'never, with 'auto being the default.

This speeds up copying large files a lot while saving the disk space.

'seek' can now navigate holes in sparse files

On systems that support it, such as GNU/Linux, the new SEEK_DATA and SEEK_HOLE values can now be passed to the 'seek' procedure to change file offset to the next piece of data or to the next hole in sparse files. See "Random Access" in the manual for details.

((scm foreign-object) make-foreign-object-type) now supports #:super

A list of superclasses can now be provided via #:super.

'get-bytevector-all' is now written in Scheme and is thus suspendable

The 'get-bytevector-all' procedure from (rnrs io ports) and (ice-9 binary-port) used to be implemented in C, making it non-suspendable--a bummer for programs using suspendable ports and Fibers. It has been rewritten in Scheme, addressing this limitation.

• Performance improvements

Better compilation of calls to procedures with keyword arguments

Calls to keyword-arg functions can now be inlined. Even when not inlined, sometimes now we can compute default values for missing keywords at the callee instead of in the caller.

Better compilation of append with more than 2 arguments Better compilation logand with one immediate argument Better type inference for result of symbol-hash Elide effect-free primitive calls when called for effect Constant folding for string->utf8 JIT improvements for rarely-used push/pop/drop Better type inference for numeric tower predicates Better compilation for calls to raise-exception Smaller disk usage via sparse binary files

• New deprecations

(ice-9 lineio)

Use read-line together with unread-string instead.

• Changes to the distribution

Parallel test driver for Guile unit tests

Guile's internal unit test harness is now compatible with Automake's parallel test driver, allowing make check -j20 to use 20 cores, if you have them. Send any bug reports to bug-guile@….

[Bruce Dubbs]

Fixed at commit 480c503e48.