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update NEWS for 1.9.2
* NEWS: Update.
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Andy Wingo
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148
NEWS
148
NEWS
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@ -10,87 +10,99 @@ prerelease, and a full NEWS corresponding to 1.8 -> 2.0.)
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Changes in 1.9.2 (since the 1.9.1 prerelease):
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** Global variables `scm_charnames' and `scm_charnums' are removed.
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** VM speed improvements
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Closures now copy the free variables that they need into a flat vector
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instead of capturing all heap-allocated variables. This speeds up access
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to free variables, avoids unnecessary garbage retention, and allows all
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variables to be allocated on the stack.
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Variables which are `set!' are now allocated on the stack, but in
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"boxes". This allows a more uniform local variable allocation
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discipline, and allows faster access to these variables.
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The VM has new special-case operations, `add1' and `sub1'.
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** VM robustness improvements
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The maximum number of live local variables has been increased from 256
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to 65535.
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The default VM stack size is 64 kilo-words, up from 16 kilo-words. This
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allows more programs to execute in the default stack space. In the
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future we will probably implement extensible stacks via overflow
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handlers.
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Some lingering cases in which the VM could perform unaligned accesses
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have been fixed.
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The address range for relative jumps has been expanded from 16-bit
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addresses to 19-bit addresses via 8-byte alignment of jump targets. This
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will probably change to a 24-bit byte-addressable strategy before Guile
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2.0.
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** Compiler optimizations
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Procedures bound by `letrec' are no longer allocated on the heap,
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subject to a few constraints. In many cases, procedures bound by
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`letrec' and `let' can be rendered inline to their parent function, with
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loop detection for mutually tail-recursive procedures.
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Unreferenced variables are now optimized away.
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** Compiler robustness
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Guile may now warn about unused lexically-bound variables. Pass
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`-Wunused-variable' to `guile-tools compile', or `#:warnings
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(unused-variable)' within the #:opts argument to the `compile' procedure
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from `(system base compile)'.
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** Incomplete support for Unicode characters and strings
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Preliminary support for Unicode has landed. Characters may be entered in
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octal format via e.g. `#\454', or created via (integer->char 300). A hex
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external representation will probably be introduced at some point.
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Internally, strings are now represented either in the `latin-1'
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encoding, one byte per character, or in UTF-32, with four bytes per
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character. Strings manage their own allocation, switching if needed.
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Currently no locale conversion is performed. Extended characters may be
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written in a string using the hexadecimal escapes `\xXX', `\uXXXX', or
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`\UXXXXXX', for 8-bit, 16-bit, or 24-bit codepoints, respectively.
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This support is obviously incomplete. Many C functions have not yet been
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updated to deal with the new representations. Users are advised to wait
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for the next release for more serious use of Unicode strings.
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** `defined?' may accept a module as its second argument
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Previously it only accepted internal structures from the evaluator.
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** `let-values' is now implemented with a hygienic macro
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This could have implications discussed below in the NEWS entry titled,
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"Lexical bindings introduced by hygienic macros may not be referenced by
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nonhygienic macros".
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** Global variables `scm_charnames' and `scm_charnums' are removed
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These variables contained the names of control characters and were
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used when writing characters. While these were global, they were
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never intended to be public API. They have been replaced with private
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functions.
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** EBCDIC support is removed.
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** EBCDIC support is removed
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There was an EBCDIC compile flag that altered some of the character
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processing. It appeared that full EBCDIC support was never completed
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and was unmaintained.
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Changes in 1.9.1 (since the 1.9.0 prerelease):
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** `scm_set_port_seek' and `scm_set_port_truncate' use the `scm_t_off' type
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Previously they would use the `off_t' type, which is fragile since its
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definition depends on the application's value for `_FILE_OFFSET_BITS'.
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** Automatically compiled files will be placed in ~/.cache, not ~/.guile-ccache.
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Actually, they will be placed in $XDG_CACHE_HOME/guile/ccache/1.9,
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defaulting to XDG_CACHE_HOME=~/.cache. Users may remove their
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~/.guile-ccache directories.
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** New language: Brainfuck.
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Brainfuck is a toy language that closely models Turing machines. Guile's
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brainfuck compiler is meant to be an example of implementing other
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languages. See the manual for details, or
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http://en.wikipedia.org/wiki/Brainfuck for more information about the
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Brainfuck language itself.
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** A number of Scheme files were corrected to be LGPLv3+.
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Some Scheme files imported for the compiler were erroneously labeled as
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being LGPLv2+ or GPLv2+. This oversight has been fixed.
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** Bytevectors may now be accessed with a C-friendly API.
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New functions: `scm_is_bytevector ()', `scm_c_bytevector_length ()',
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`scm_c_bytevector_length ()', and `scm_c_bytevector_set_x ()'. See the
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manual for details.
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** Bytevectors are now accessible using the generalized-vector API.
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As a side effect, this change allows compilation of literal bytevectors
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(`#vu8(...)').
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** Meta-commands to the REPL work better with strange languages.
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Specifically, meta-commands that take expressions as arguments will use
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the current language's reader to read those expressions, which may span
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multiple lines, with readline integration if the user has that enabled.
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** The object code file format has changed.
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The objcode loader will complain about a "bad header cookie" if it
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happens to find an old file. The workaround for that is currently to
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find all stale .go files and remove them. This is likely to affect users
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who have checked out Guile's git repository, not those that build from
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tarballs.
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** Vector access has been sped up considerably.
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Guile's virtual machine now has vector and bytevector operations. Using
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Guile to process large amounts of data is now easier. This is because
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`vector-ref' and `vector-set!' now have fast opcodes. In addition, there
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are opcodes for `ref' and `set' operations on bytevectors for everything
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from 8-bit integers to 64-bit floating-point values.
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In the next release, we hope to extend this speedup to other kinds of
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uniform vectors.
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** The `long_long' C type, deprecated in 1.8, has been removed.
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** And of course, the usual collection of bugfixes.
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** And of course, the usual collection of bugfixes
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Interested users should see the ChangeLog for more information.
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Changes in 1.9.x (since the 1.8.x series):
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* New modules (see the manual for details)
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