prefer compilers earlier in list

[bpt/guile.git] / NEWS

diff --git a/NEWS b/NEWS
index 2c13fb7..208ec9e 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,5 @@
 Guile NEWS --- history of user-visible changes.
 Guile NEWS --- history of user-visible changes.

-Copyright (C) 1996-2014 Free Software Foundation, Inc.
+Copyright (C) 1996-2015 Free Software Foundation, Inc.

 See the end for copying conditions.
 
 Please send Guile bug reports to bug-guile@gnu.org.
 See the end for copying conditions.
 
 Please send Guile bug reports to bug-guile@gnu.org.


@@ -25,13 +25,28 @@ Notably, weak hash tables are now transparently thread-safe.  Ports are
 also thread-safe; see "New interfaces" below for details on the changes
 to the C interface.
 
 also thread-safe; see "New interfaces" below for details on the changes
 to the C interface.
 

+** Better space-safety
+
+It used to be the case that, when calling a Scheme procedure, the
+procedure and arguments were always preserved against garbage
+collection.  This is no longer the case; Guile is free to collect the
+procedure and arguments if they become unreachable, or to re-use their
+slots for other local variables.  Guile still offers good-quality
+backtraces by determining the procedure being called from the
+instruction pointer instead of from the value in slot 0 of an
+application frame, and by using a live variable map that allows the
+debugger to know which locals are live at all points in a frame.
+

 ** Off-main-thread finalization
 
 Following Guile 2.0.6's change to invoke finalizers via asyncs, Guile
 2.2 takes the additional step of invoking finalizers from a dedicated
 finalizer thread, if threads are enabled.  This avoids concurrency
 issues between finalizers and application code, and also speeds up
 ** Off-main-thread finalization
 
 Following Guile 2.0.6's change to invoke finalizers via asyncs, Guile
 2.2 takes the additional step of invoking finalizers from a dedicated
 finalizer thread, if threads are enabled.  This avoids concurrency
 issues between finalizers and application code, and also speeds up

-finalization.
+finalization.  If your application's finalizers are not robust to the
+presence of threads, see "Foreign Objects" in the manual for information
+on how to disable automatic finalization and instead run finalizers
+manually.

 
 ** Better locale support in Guile scripts
 
 
 ** Better locale support in Guile scripts
 


@@ -65,14 +80,35 @@ loop that collect its results in reverse order only to re-reverse them
 at the end, now you can just recurse without worrying about stack
 overflows.
 
 at the end, now you can just recurse without worrying about stack
 overflows.
 

+Using the stack also allows more code to be continuation-safe.  For
+example, returning multiple times from a `map' procedure in Guile 2.0
+would change the value of previously returned result lists, because
+`map' built its result list in reverse order then used `reverse!' to
+return the proper result.  Now in Guile 2.2, `map' is implemented using
+straightforward recursion, which eliminates this bug while maintaining
+good performance as well as good space complexity.
+
+** Out-of-memory improvements
+
+Instead of aborting, failures to allocate memory will now raise an
+unwind-only `out-of-memory' exception, and cause the corresponding
+`catch' expression to run garbage collection in order to free up memory.
+
+** GOOPS core reimplemented in Scheme
+
+Guile's object orientation system, GOOPS, has been mostly reimplemented
+in Scheme.  This decreases its maintenance burden on the rest of Guile,
+while also makes it possible to implement new features in the future,
+such as method combinations or `eqv?' specializers.
+

 * Performance improvements
 
 ** Faster programs via new virtual machine
 
 * Performance improvements
 
 ** Faster programs via new virtual machine
 

-Guile's new virtual machine compiles programs to instructions for a new
-virtual machine.  The new virtual machine's instructions can address
-their source and destination operands by "name" (slot).  This makes
-access to named temporary values much faster, and removes a lot of
+Guile now compiles programs to instructions for a new virtual machine.
+The new virtual machine's instructions can address their source and
+destination operands by "name" (slot).  This makes access to named
+temporary values much faster than in Guile 2.0, and removes a lot of

 value-shuffling that the old virtual machine had to do.  The end result
 is that loop-heavy code can be two or three times as fast with Guile 2.2
 as in 2.0.  Your mileage may vary, of course; see "A Virtual Machine for
 value-shuffling that the old virtual machine had to do.  The end result
 is that loop-heavy code can be two or three times as fast with Guile 2.2
 as in 2.0.  Your mileage may vary, of course; see "A Virtual Machine for


@@ -95,9 +131,11 @@ as well.  See "Object File Format" in the manual, for full details.
 Guile's compiler now uses a Continuation-Passing Style (CPS)
 intermediate language, allowing it to reason easily about temporary
 values and control flow.  Examples of optimizations that this permits
 Guile's compiler now uses a Continuation-Passing Style (CPS)
 intermediate language, allowing it to reason easily about temporary
 values and control flow.  Examples of optimizations that this permits

-are optimal contification, dead code elimination, parallel moves with at
-most one temporary, and allocation of stack slots using precise liveness
-information.  For more, see "Continuation-Passing Style" in the manual.
+are optimal contification, optimal common subexpression elimination,
+dead code elimination, parallel moves with at most one temporary,
+allocation of stack slots using precise liveness information, and
+closure optimization.  For more, see "Continuation-Passing Style" in the
+manual.

 
 ** Faster interpreter
 
 
 ** Faster interpreter
 


@@ -125,6 +163,12 @@ its string hash, and Thomas Wang's integer hash function for `hashq' and
 `hashv'.  These functions produce much better hash values across all
 available fixnum bits.
 
 `hashv'.  These functions produce much better hash values across all
 available fixnum bits.
 

+** Optimized generic array facility
+
+Thanks to work by Daniel Llorens, the generic array facility is much
+faster now, as it is internally better able to dispatch on the type of
+the underlying backing store.
+

 * New interfaces
 
 ** New `cond-expand' feature: `guile-2.2'
 * New interfaces
 
 ** New `cond-expand' feature: `guile-2.2'


@@ -180,10 +224,6 @@ For more on `SCM_HAS_TYP7', `SCM_HAS_TYP7S', `SCM_HAS_TYP16', see XXX.
 the old `SCM2PTR' and `PTR2SCM'.  Also, `SCM_UNPACK_POINTER' yields a
 void*.
 
 the old `SCM2PTR' and `PTR2SCM'.  Also, `SCM_UNPACK_POINTER' yields a
 void*.
 

-** `scm_c_weak_vector_ref', `scm_c_weak_vector_set_x'
-
-Weak vectors can now be accessed from C using these accessors.
-

 ** <standard-vtable>, standard-vtable-fields
 
 See "Structures" in the manual for more on these
 ** <standard-vtable>, standard-vtable-fields
 
 See "Structures" in the manual for more on these


@@ -198,6 +238,20 @@ See XXX for more on `scm_from_port_string', `scm_from_port_stringn',
 See "PEG Parsing" in the manual for more.  Thanks to Michael Lucy for
 originally writing these, and to Noah Lavine for integration work.
 
 See "PEG Parsing" in the manual for more.  Thanks to Michael Lucy for
 originally writing these, and to Noah Lavine for integration work.
 

+** `make-stack' now also works on delimited continuations
+
+** Better URI-reference support
+
+The `(web uri)' module now has interfaces for handling URI references,
+which might not have a scheme.  The Location header of a web request or
+response is now a URI reference instead of a URI.  Also,
+`request-absolute-uri' now has an optional default scheme argument.  See
+"Web" in the manual for full details.
+
+** formal-name->char, char->formal-name
+
+See "Characters", in the manual.
+

 * Incompatible changes
 
 ** ASCII is not ISO-8859-1
 * Incompatible changes
 
 ** ASCII is not ISO-8859-1


@@ -340,15 +394,82 @@ of compiling to objcode and then calling `make-program', now the way to
 do it is to compile to `bytecode' and then call `load-thunk-from-memory'
 from `(system vm loader)'.
 
 do it is to compile to `bytecode' and then call `load-thunk-from-memory'
 from `(system vm loader)'.
 

-** Remove weak pairs.
+** Weak pairs removed

 
 Weak pairs were not safe to access with `car' and `cdr', and so were
 removed.
 
 
 Weak pairs were not safe to access with `car' and `cdr', and so were
 removed.
 

-** Remove weak alist vectors.
+** Weak alist vectors removed

 
 Use weak hash tables instead.
 
 
 Use weak hash tables instead.
 

+** Weak vectors may no longer be accessed via `vector-ref' et al
+
+Weak vectors may no longer be accessed with the vector interface.  This
+was a source of bugs in the 2.0 Guile implementation, and a limitation
+on using vectors as building blocks for other abstractions.  Vectors in
+Guile are now a concrete type; for an abstract interface, use the
+generic array facility (`array-ref' et al).
+
+** scm_t_array_implementation removed
+
+This interface was introduced in 2.0 but never documented.  It was a
+failed attempt to layer the array implementation that actually
+introduced too many layers, as it prevented the "vref" and "vset"
+members of scm_t_array_handle (called "ref" and "set" in 1.8, not
+present in 2.0) from specializing on array backing stores.
+
+Notably, the definition of scm_t_array_handle has now changed, to not
+include the (undocumented) "impl" member.  We are sorry for any
+inconvenience this may cause.
+
+** `scm_make' is now equivalent to Scheme `make'
+
+It used to be that `scm_make' only implemented a hard-wired object
+allocation and initialization protocol.  This was because `scm_make' was
+used while GOOPS booted its own, more complete `make' implementation in
+Scheme.  Now that we've re-implemented everything in Scheme, the C
+`scm_make' now dispatches directly to Scheme `make', which implements
+the full protocol.  This change is incompatible in some ways, but on the
+whole is good news for GOOPS users.
+
+** GOOPS slot definitions are now objects
+
+Slot definitions are now instances of a <slot> class, instead of being
+specially formatted lists.  To most user code, this is transparent, as
+the slot definition accessors like `slot-definition-name' continue to
+work.  However, code that for example uses `car' to get the name of a
+slot definition will need to be updated to use the accessors.
+
+** Class slot changes
+
+Class objects no longer have a `default-slot-definition-class' slot,
+which was never used.  They also no longer have slots for hashsets
+(`h0', `h1', and so on up to `h7'), which have been unused since Guile
+2.0 and were not a great idea.
+
+There is a new class option, `#:static-slot-allocation?'.  See the
+manual for details.
+
+** Removal of internal, unintentionally exposed GOOPS C interfaces
+
+These include: `scm_sys_fast_slot_ref', `scm_sys_fast_slot_set_x'
+`scm_basic_basic_make_class', `scm_sys_compute_slots',
+`scm_sys_prep_layout_x' `scm_t_method', `SCM_METHOD',
+`scm_s_slot_set_x', `SCM_CLASS_CLASS_LAYOUT', `scm_si_slotdef_class',
+`scm_si_generic_function', `scm_si_specializers', `scm_si_procedure',
+`scm_si_formals', `scm_si_body', `scm_si_make_procedure',
+`SCM_CLASS_CLASS_LAYOUT', `SCM_INSTANCE_HASH', `SCM_SET_HASHSET', `union
+scm_t_debug_info', `scm_pure_generic_p', `SCM_PUREGENERICP',
+`SCM_VALIDATE_PUREGENERIC', `SCM_VTABLE_FLAG_GOOPS_PURE_GENERIC',
+`SCM_CLASSF_PURE_GENERIC', `scm_c_extend_primitive_generic',
+`scm_sys_initialize_object', `SCM_CLASS_CLASS_LAYOUT',
+`scm_si_redefined', `scm_si_direct_supers', `scm_si_direct_slots',
+`scm_si_direct_subclasses', `scm_si_direct_methods', `scm_si_cpl'
+`scm_si_slots', `scm_si_getters_n_setters', `SCM_N_CLASS_SLOTS',
+`SCM_OBJ_CLASS_REDEF', `SCM_INST', `SCM_ACCESSORS_OF',
+`scm_sys_allocate_instance', and `scm_sys_invalidate_class_x'.
+

 * New deprecations
 
 ** SCM_WTA_DISPATCH_0, SCM_WTA_DISPATCH_1, SCM_WTA_DISPATCH_2, SCM_WTA_DISPATCH_N
 * New deprecations
 
 ** SCM_WTA_DISPATCH_0, SCM_WTA_DISPATCH_1, SCM_WTA_DISPATCH_2, SCM_WTA_DISPATCH_N


@@ -360,6 +481,47 @@ replaced by using C functions (the same name but in lower case), if
 needed, but this is a hairy part of Guile that perhaps you shouldn't be
 using.
 
 needed, but this is a hairy part of Guile that perhaps you shouldn't be
 using.
 

+** scm_compute_applicable_methods and scm_find_method
+
+Use `compute-applicable-methods' from Scheme instead.
+
+** scm_no_applicable_method
+
+Fetch no-applicable-method from the GOOPS exports if you need it.
+
+** scm_class_boolean, scm_class_char, scm_class_pair
+** scm_class_procedure, scm_class_string, scm_class_symbol
+** scm_class_primitive_generic, scm_class_vector, scm_class_null
+** scm_class_real, scm_class_complex, scm_class_integer
+** scm_class_fraction, scm_class_unknown, scm_class_top
+** scm_class_object, scm_class_class, scm_class_applicable
+** scm_class_applicable_struct, scm_class_applicable_struct_with_setter
+** scm_class_generic, scm_class_generic_with_setter, scm_class_accessor
+** scm_class_extended_generic, scm_class_extended_generic_with_setter
+** scm_class_extended_accessor, scm_class_method
+** scm_class_accessor_method, scm_class_procedure_class
+** scm_class_applicable_struct_class, scm_class_number, scm_class_list
+** scm_class_keyword, scm_class_port, scm_class_input_output_port
+** scm_class_input_port, scm_class_output_port, scm_class_foreign_slot
+** scm_class_self, scm_class_protected, scm_class_hidden
+** scm_class_opaque, scm_class_read_only, scm_class_protected_hidden
+** scm_class_protected_opaque, scm_class_protected_read_only
+** scm_class_scm, scm_class_int, scm_class_float, scm_class_double
+** scm_port_class, scm_smob_class
+
+These class exports are now deprecated.  Instead, look up the ones you
+need from the GOOPS module, or use `scm_class_of' on particular values.
+
+** scm_get_keyword
+
+Instead from Scheme use kw-arg-ref or real keyword arguments, and from C
+use `scm_c_bind_keyword_arguments'.
+
+** scm_slot_ref_using_class, scm_slot_set_using_class_x
+** scm_slot_bound_using_class_p, scm_slot_exists_using_class_p
+
+Instead use the normal `scm_slot_ref' and similar procedures.
+

 * Changes to the distribution
 
 ** New minor version
 * Changes to the distribution
 
 ** New minor version