Release Notes

Version 3.3 (Pignoletto)

The CURL Package

The PITA Package

Answer Subsumption

The RDF Package

Tabling and System Enhancements

• New declarations: table preds as properties and dynamic preds as properties. Since XSB allows a variety of tabling functionalities, new declarations have been added to allow users to specify properties more succinctly for tabled and dynamic predicates. Tabling properties can now be dynamically changed in certain cases (i.e., from call variance to call subsumption and from non-incrmental to incremental).
• The XSB compiler can now support multiple external preprocessors, and so can more easily support language extensions that are translated into Prolog.
• Incremental tabling is extended so that tables can be updated based on changes to trie-interned facts
• abolish_table_call/[1,2] is now implemented for predicates that use call subsumption.
• A depth check for tabled subgoals, settable by a flag, can help catch programs for which XSB's tabling may not terminate.

Other Libraries

• The Perl-Compatable Regular Expressions Library (PCRE) This package employs the PCRE library to enable XSB perform pattern matching and string substitution based on Perl regular expressions.
• The proc_files library allows XSB to load, store, and manipulate files in delimiter-separated formats (e.g. csv files).
• The xref library can be used to build a database of predicate definitions and usages among various files in a directory.

Compatability Improvements

• Support for the Prolog Commons Initiative. Conditional compilation is now supported, as is predicate renaming throught the import as construct.
• Support for the ISO Core and Core Revision Standards. The ISO include/1 predicate is now supported, forall/2 now implemented, ground/1 is now standard (and faster), new arithmetic functions have also been implemented, and meta_predicate/2 is now supported.
• Other compatability measures. XSB-specific flags are now available as Prolog flags, and new non-ISO flags have been added that are common to other Prologs. statistics/2 has been implemented for various tags, and findall/4 is now implemented and standard. The functionality of predicate_property/2 has been expanded to include the module of a predicate, along with various tabling properties.

Stability Improvements

Version 3.2 (Kopi Lewak)

Constraint libraries

Improved tabling with call subsumption

Compatibility with ISO standards

• Core ISO Standard XSB is now in closer accord with the core ISO standard in its handling of arithmetic expressions and exception handling for various ISO predicates; in addition sub_atom/5 and char_code/2 are now implemented, as are evaluable functions **/2 and sign/1.
• Core Revision ISO predicates call_cleanup/2, call/[2-10], evaluable functions '><'/2 and arithmetic constants pi/0 and e/o are now implemented. The built-in predicate predicate_property/2 now supports the property "built_in". In addition, user_error, user_warning, and user_message stream aliases have been added.
• Draft ISO Multi-Threading Standard Aliases for ISO-style mutexes are now better supported, and thread_create/2 allows specification of an on_exit handler.

Improved compatibility with other Prologs and installation

Limited support for statistics/2 is also now available. time/1 also added, for compatibility with SWI and YAP. Also, multifile now fully supports dynamic and static predicates.

Speed Improvements

Improvements to 64-bit evaluation

Improvements in multi-threading

For private tables Version 3.2 provides greatly improved scalability. For shared tables under local evaluation (shared completed tables), more concurrency is now possible and fewer thread wake-ups now occur. Code is also more robust in (pathological) cases of cascading usurpations.

Foreign-Language Interface

Interned Tries

XASP package

dbdrivers package

Profiling

random.P

Memory management

table garbage collection has more thorough reclamation of abolished table space. In addition, table garbage collection now checks delay lists so that garbage collection within non-stratified queries is safer.

Version 3.1 (Incognito)

Major Improvements

• 64-bit compilation Both the single-threaded and multi-threaded engines of XSB have been thoroughly tested on 64-bit Linux. All XSB functionality and packages now work when XSB is compiled on such platforms using either 64-bit or 32-bit compilation.
• Incremental tabling Incremental tabling has been added for programs that use tabling with call-variance on program fragments that do not require tabled negation. If a table depends on dynamic code (perhaps indirectly) asserts or retracts to the code will propagate incremental changes to the various depending tables. Thus the tables are updated automatically and incrementally with respect to changes in fluents, rather than having to be explicitly recomputed.
• Multi-threading improvements The multi-threaded engine is faster and far more robust than in previous versions. Libraries have been expanded for the multi-threaded engine as well.
• A single query can now safely intermix private and shared tables, even if can depend on each other in the same SCC or depend through conditional answers in the well-founded semantics.
• Heap garbage collection now can occur for any thread independently of any other thread.
• Improvements have been made for thread, mutex, and message queue management, usually based on ISO working document ISO/IEC DTR 13211{5:2007} with which XSB is now mainly in compliance:
• Private and shared unification-based message queues are now supported, user-level mutex are now supported, as are thread, mutex, and queue aliases.
• Thread creation allows a number of parameters to be passed in via an option list, or alternately taken from settable defaults. In addition, thread cancellation now cancels threads when they are waiting for messages or are blocked on I/O.
• Specific to XSB, examples have been added so that XSB can used as a multi-threaded server with socket-based communication. The regexp, wildmatch, and libwww libraries have been ported to the multi-threaded engine.
• Improved C-calling XSB interface
• XSB now behaves better when embedded in a C process. When XSB encounters an error, it uses a mechanism to pass the error back to C. Errors that cause XSB to exit when called as a stand-alone server have the type "unrecoverable error".
• Query caching has been added to the C/XSB interface to make repeated queries to XSB more efficient.
• The C-calling XSB interface has also been updated for the multi-threaded engine so that a given XSB thread can be safely queried by multiple C (or Java) threads, a facility that works for the varstring, fixed string, and register interfaces. Within a multi-threaded system XSB threads can maintain the state of queries if desired so that they function analogously to cursors in a database.
• Improved memory management for tables
• When a given tabled subgoal (predicate) T1 is abolished, any tabled subgoal (predicate) T2 that depends conditionally on T1 will also be abolished by default (this behavior can be altered by a flag, or by using an option list).
• All space for conditional answer information is now reclaimed when space for a tabled predicate or subgoal is reclaimed after an abolish or simplification operation. In addition, all information for private tables, including conditional table information is thread-private, and is reclaimed upon a thread's exit.
• Added structure manager for private hash tables in tries. In addition, each shared structure manager now has its own mutex in the multi-threaded engine. These changes should improve scalability of tables in the shared engine.
• Detailed statistical information is not available on all table structures, including those for conditional answers. In the multi-threaded engine, this information is available for both shared tables and tables private to the calling thread.
• Two new predicates are added for table management in the multi-threaded engine: abolish_all_shared_tables/0 and abolish_all_private_tables/0.
• Improvements to dynamic clause garbage collection
• Dynamic clause garbage collection for private dynamic predicates now uses private structure managers to improve concurrency for retracting private clauses.
• Dynamic clause garbage collection has been tuned to be more efficient for routines that call retract(all) repeatedly.
• Improved ISO compatibility for numerous cases of error handling. With relatively minor exceptions, XSB now generally throws ISO-compliant errors for ISO predicates.
• Improvements in Interned Tries Library XSB provides interned tries as an extremely efficient way of adding and deleting terms to a global store (private to each thread):
• The API for interned tries was redesigned to make it simpler to use, and in some cases more efficient. Error checking has been added to make the library more robust.
• To check whether a trie may be backtracked over before deleting a trie, or expanding its hash table.
• New syntax for tables allows concise declarations of various attribute combinations, including whether the predicate is to use call subsumption or call variance, is dynamic or static, is private or shared, and is incremental.

Other Improvements

• XSB's compiler now make XSB's compilation much faster for files with large predicates, as well as when compiling strings. In addition, generated code now has fewer instructions in some cases.
• XSB's canonical term reader significantly improves the time to dynamically load a canonical file.
• Register allocation works better when asserting large clauses.
• Allocation of memory for sorting routines -- this improves times and concurrency of programs that use sorting heavily, such as set-based analysis.
• Added a constraint library allowing variable ordering, when/2, and unifiable/2.
• Added exp/2 as an evaluable function.
• Basic term coloring and other syntactic features are supported for the editor BBEdit.

Bug fixes

• Heap overflows when copying large terms out of a table are now uniformly caught, as well as pdl stack overflows when copying large terms into or out of a table.
• Heap overflows during compilation of large clauses are now uniformly caught.
• Cases are now handled properly where a mixture of table abolish predicates are called on similar tabled predicates and subgoals that are not ready to be reclaimed. Similarly, repeated abolishes and re-generation of tables in computation states where their space cannot be reclaimed is now handled properly.
• Garbage collecting dynamic clauses on predicates with multiple or combined indices is now handled properly
• The number of string interns used on reads and other actions has been reduced, a change useful for thread scalability.
• Problems with error handling stemming from reloading the system file standard.P are now avoided.
• Buffer overflows in file_read_line_list/[1,2] are now avoided under all conditions
• Errors in loading large compiled Flora files are now avoided.
• Problems with handling streams in the format library are now fixed.
• Performing simplification of shared tables in the multi-threaded engine is now mutexed properly.
• FreeBSD is now recognized in higher-level XSB calling C interface
• Calls to the atom-table garbage collector are now avoided when more than one thread is active.
• Bugs in performing heap garbage collecting under certain conditions when constraint interrupts have been scheduled but not executed have now been fixed.
• Numerous small memory problems have been fixed in the various engines as exposed by Valgrind. These fixes particularly improve the stability of applications that may use conditional answers, such as Flora.
• Fixed debugger to work properly with CHR programs.
• Fixed bug in handling lists in unify_with_occurs_check/2.

Version 3.0 (Sagres)

General

Version 3.0 is a major rewriting of the XSB engine to support multi-threading and to include many new and improved features.

Major New Functionality

• The XSB engine has been entirely rewritten to allow a user to create and run multiple XSB threads within a single process on both Unix and Windows. Thread manipulation is based on the semantics of Posix threads, and includes major Posix-style operations such as detaching, joining, and canceling threads. The engine has been designed to allow hundreds of threads to execute concurrently, including asserting and retracting dynamic code, creating and abolishing tables, and performing I/O. To support this, dynamic predicates and tables are considered to be thread-private by default, but may also be declared to be shared among threads when appropriate.
• Improved garbage collection routines have been written to reclaim space for dynamic clauses, SLG tables, and Prolog atoms. Garbage collection for thread-private dynamic clauses and tables, can occur concurrently in multiple threads.
• XSB now supports 32-bit integer and 64-bit float computation by default.
• A new package, CHRd has been added. CHRd is an alternative implementation of Constraint Handling Rules, which uses a distributed storage of constraints and a set-based operational semantics. The distributed storage of constraints can lead to efficiencies when tabling predicates within a CHR framework.

Other Functionality

• A number of changes have been made to make XSB more compatible with the ISO standard for Prolog. Changes have been made to XSB's scanning of atoms and numbers, exception handling, and to handling of undefined predicates. In addition, Version 3.0 includes the new ISO predicates unify_with_occurs_check/2, atom_length/2 and initialization/1 .
• The compiler now generates more efficient code for deterministic tests within conditionals.
• Several changes have been made to support (non ISO) compatibility with other Prologs.
  • XSB's compiler and consult mechanism now recognizes files with a .pl extension as well as a .P extension.
  • Clauses for dynamic predicates can now be included in statically compiled files.
  • min/1 and max/1 are now included as arithmetic functions.
• The following predicates provide new functionality beyond that discussed.
  • term_to_atom/3 allows an atom to be created from a term using the write options familiar from write_term/3.
  • statistics provides a much more detailed account of how program memory is used.
  • New predicates, abolish_module_tables/1, abolish_private_tables/0, and abolish_shared_tables/0 allow greater flexibility for invalidating tables for sets of predicates.

Version 2.7.1 (Kinryo)

Version 2.7.1 is a minor release whose main changes are to support the tagging required by newer versions of Linux, as well as to support foreign language calls and packages on the Apple Macintosh. Other bug fixes and functionality improvements have also been made.

• A new tagging scheme has been created to handle tagging on newer versions of Linux. The choice of tagging is made automatically by XSB's configuration mechanism.
• The XSB/C foreign language interface is now supported under Macintosh OS X. In addition, fixes have been made to perlmatch regmatch, and wildmatch to support these packages on OS X. These patches were submitted by Barry Evans.
• ODBC Package: Added odbc_sql_cnt/4 predicate to be used to call an Update, insert, or delete SQL statement. It returns the number of affected rows in the fourth parameter of the call. Also added support for use of iodbc (www.iodbc.org) driver manager.
• Fixed bug in setof in handling variables in template and patterns. The fix was submitted by Bart Demoen and Kostis Sagonas.
• .cpp files can now be compiled, loaded and called from XSB.
• Changed write_canonical to write more complete floating point numbers.
• New packages sgml and xpath have been added. The sgml package can parse XML, HTML, and even SGML; it is adapted from SWI Prolog. The xpath package supports XPath queries to XML documents.

Version 2.7 (Kinryo)

General

Version 2.7 has many fixes to bugs and improvements to packages and libraries.

Major New Functionality

• The Constraint Handling Rules package includes both a CHR runtime system and a compiler to convert CHR files to Prolog files. This packages allow CHR to be used with tabling, and includes several sample CHR solvers that have been ported to XSB.
• ISO-style streams are now supported by all XSB file I/O. Streams can be used to access strings and pipes as well as files, and the distinction between I/O streams and I/O ports has been removed. New I/O and other predicates to support ISO functionality have also been added.
• The dbdrivers package provides functionality to manage multiple drivers and databases from XSB, and currently supports ODBC and mysql drivers.
• XSB now has the capability to determine the proportion of time spent in each predicate and module via the XSB Profiling library.
• XSB now prints out the forward and backward execution stacks upon unhandled errors, allowing for better debugging. This facility is on by default, but can be turned off using an XSB flag.
• A new faculty xsb_lint has been created to help determine which predicates must be exported and imported into files upon modularization. Through the statements document_export/1 and document_import/1, Version 2.7 also supports "pseudo-modules". Such files act as are regular files in terms of execution, but their declarations are used by xsb_lint, xsbdoc and the compiler's use inference pass.

Other Functionality

• Functionality for use inference, a part of XSB's compiler has been expanded. Use inference now checks standard meta-predicates (e.g. findall, assert) for usage.
• The predicate parsort/4 has been added to provide efficient and flexible sorting. It can sort different argument positions of predicates lexicographically, in either ascending or descending order, and either eliminate duplicates or not.
• A new built-in set_file_write_depth/1 controls the depth of terms printed by standard I/O built-ins.
• Improvements have been made to the compiler for efficiency, and several bug fixes have been made to compiling and parsing. In addition, singleton_warnings_off a new compiler option suppresses singleton warnings by the compiler, and so is useful for code generation.
• Improvements have been made to the ODBC interface, to allow multiple ODBC connections, to allow querying of information about the ODBC connection itself, and to allow data to be retrieved as character lists rather than as atoms.
• XSB disassembler output is now readable by Prolog.
• Predicates defined within a module, but not exported can be called from outside that module using the call Module:Call. The predicate @=/2 has been added that succeeds if two terms are identical variables, or if the main functor symbols of two terms to be compared are identical, and fails otherwise.
• Improvements have been made to memory management, to better integrate heap garbage collection and heap stack expansion.

Selected Bug Fixes

• Java 1.4.2 introduced some incompatibilities in memory management which broke InterProlog. This has been fixed in this version. In addition, parameters may now be passed when invoking XSB from Java.
• The GPP pre-processor has been updated. Most notably among the new functionalities is that #include can, now, take a macro as an argument.
• XSB's stack reallocation is now aware of attributed variables and interrupt handlers.
• An inconsistency in the handling of declarations has been fixed. The inconsistency involved different handling of predicate names declared as P/A and P(_,_,_,...).
• message/2 has been fixed to properly deal with a list as its 1st argument.
• A long-standing register allocation bug in the compiler is now fixed.
• Optimizations and bug fixes have been made to the XASP Smodels interface.
• Various error fixes and improvements made to xsbdoc.

Backward Incompatibility

• The implementation and interface of attributed variables has been changed to fix several inconsistencies and to allow attributes in different modules. These changes were necessary for the CHR implementation and made the CLP(R) implementation unavailable. CLP(R) style handling is available through CHR solvers included in the CHR package.
• The Oracle interface is no longer supported. Its functionality can be obtained through either XSB's ODBC interface or through the new dbdrivers package.

Version 2.6 (Duff)

General

Version 2.6 contains a number of changes, including new packages and libraries for generation of manuals from code documentation and for answer set programming. Version 2.6 also allows a user-modifiable extension for byte-code files, whose default .xwam extension replaces the previous .O extension. Existing features Version 2.6 have been improved in various ways, from better exception handling, to a more robust Windows implementation, to numerous bug-fixes.

News

• The Chat engine has been removed. An optimized version of the SLG-WAM is now the single engine supported in XSB. The garbage collectors have been ported to this engine.
• Various aspects of XSB have been rewritten to support an ISO-compatible error handling mechanism in which exceptional conditions can be caught and handled by user programs.
• Fixed-depth indexing has been added for dynamic predicates. Using fixed-depth indexing a term in a given arguments may be indexed on the first five non-variable symbols. Multiple-argument and alternative indices also work with fixed-depth indexing just as they do with outer functor indexing.
• Full-word integers are now supported in XSB via an implementation of boxed integers.
• Date and time routines have been added as standard predicates.

Packages and Libraries

• A new package, xsbdoc, has been added. xsbdoc supports a "literate programming" style, in which code-level comments can be used to generate manuals. It is based in part on Ciao system's lpdoc.
• The XASP package provides an efficient interface to SModels from XSB. It is a significant rewrite of the previous SModels interface.
• An ODBC interface to MySQL is now supported under Linux. In addition, Prolog terms can now be written to and read from database strings.
• A new library, stdscan.P is provided containing a configurable scanner for text parsing.
• Updates to the major packages, including Flora-2 and XMC.

Platform stabilization

• Stability of XSB on Windows has been improved in many ways, both when XSB is compiled with Cygwin/GCC, and when compiled by native windows compilers. These changes include a better configuration mechanism for Windows, a robust XSB-calling-C interface, and better support for gpp preprocessing of Prolog files. In addition, many standard and library predicates have been stabilized for Windows, including cputime/1, directory query routines, path and file handling, the format.P library, and others.
• The build process has been fixed for 64-bit MIPS machine. XSB should be easily portable to most 64-bit machines.

Bugfixes

• Several bugfixes have been made for the CLP(R) package, including expansion of math functions to include min/1, max/1, and pow/2.
• Hashing function have been changed to provide better indexing of longish strings.
• Various bugs in pathname handling were fixed, and differences in pathname handling between Unix and Windows were minimized.
• Bugs closed since last release (see Bugs for more information): #585031, #569972, #723875, #535270, #683785, #666940, #637782, #635399, #524348, #626921, #449237, #706145, #641852, #638830, #642024, #535257, #529566, #475363, #589668, #531264

Backward Incompatibility

• The object files now have the .xwam extension instead of the .O extension.
• The xsb_undefined_predicate_hook has been deprecated. Instead, XSB now throws the exception of the form error(undefined_predicate(Name,Arity,ModName),ErrorMessage) when an undefined predicate is called. This exception can be caught and appropriate action can be taken.

Version 2.5 (Okocim)

General

This is mostly a transitional release, where the major changes are the move to use the SLG-WAM engine as default, and the introduction of garbage collection support for this engine. Also, several important memory management related bugs have been fixed, increasing the system's stability considerably.

Important Note

This is the last release to support the Chat engine.

News

• SLG-WAM stack management has been made the default rather than Chat. Chat is still available through a configuration option.
• A new heap garbage collector, called indirect has been made the default garbage collector for SLG-WAM. In addition, the Chat sliding and copying garbage collectors now also work on the SLG-WAM configuration.
• New builtins round/2, ceil/2 and floor/2 for dealing with floating point numbers added.

Bugfixes

• Several memory management related bugs fixed.
• Minor bug in Prolog debugger fixed.
• Fixed problem with NULL values and ODBC.

Backward Incompatibility

• None

FLORA News

Flora-2 is still a late alpha release, but there have been considerable improvements in stability and speed. This release fixes many bugs, eliminates some restrictions, and adds new features.

• The most important new feature is the ability to check for undefined predicates and methods in debug mode (see the manual regarding checking undefinedness checks). This feature simplifies debugging considerably.
• Flora compiler now checks if a tabled predicate depends on an update operation and issues appropriate warnings. Such dependency is considered to be a likely program bug.
• Numbered anonymous oids added (e.g., _#123). They behave like regular anonymous oids (_#) in the sense that they are substituted by a new oid. However, numbered oids can be referenced within the same clause (e.g., _#12[self->_#12]).
• Optimized compilation of path expressions and nested terms.

Version 2.4 (Bavaria)

General

News

• XSB now permits user programs to register hooks to be called when an undefined predicate is encountered. This and other (previously undocumented) hooks are described in the chapter titled Hooks in Manual Part 1.
• The XMC Model Checking System is now included as a package in XSB.
• Local scheduling has been made the default scheduler.
• Uniform interface to various file operations (chdir, isdir, readable, etc.) through the predicate path_sysop/2 and path_sysop/3 (in module file_io). See Manual, Part 2 (Script Utilities).
• New string matching function, string_match/4, which extends str_sub/3 (string_match/4 doesn't do pattern matching - use the regmatch package for that). See Manual, Part 2, (String Manipulation).

Bugfixes

• Fixed subsumption bug prompted by certain uses of functors and lists. The bug appeared as an inability to unify a (falsely identified) answer with an answer template.

Backward Incompatibility

• The meaning of argument 3 in predicate str_sub/3 has changed. It still represents the position of the substring match. However, offsets now start from 0, like other string functions, instead of 1.
• A number of new predicates have been added as a step towards ISO compatibility.

FLORA News

This release of XSB contains an alpha release of a completely redesigned and re-implemented FLORA system (now called FLORA-2). Here is an incomplete list of the main new features of the system:

• Integrates F-logic, HiLog, and Transaction Logic into one coherent language
• Provides a new, flexible module system
• Better equality maintenance and support for inheritance
• Support for preprocessing
• Many more enhancements

We recommend that Flora users should start using Flora-2, as the previous version of Flora is no longer maintained and will eventually be deprecated.

Version 2.3 (Zombie)

General

A great number of bugs fixed, new features, performance improvements.

News

• Subsumption: In addition to variant-based tabling, XSB now provides tabling based on subsumption of calls. In such a "subsumption-based" tabled evaluation, answers from a more general subgoal are used to satisfy a subsumed (more specific) subgoal, thereby permitting greater reuse of computed results. The tabling strategy may be chosen on a per predicate basis. Subsumption-based tabling typically yields better performance in both time and space. However, subsumptive tabling is better suited to more declarative programs, as it may fail to give proper results in the presence of certain Prolog constructs such as var/1. This implementation of subsumption-based tabling correctly evaluates normal logic programs which do not require subgoal delays.
• Jumptable Emulator: The system is now able to take advantage of special gcc features to implement a jumptable-based emulator, which speeds up XSB considerably.
• Sockets: XSB now supports the socket select call and timeouts.
• RDF parser: The XSB libwww package that first appeared in XSB 2.2 now has new interface to the RDF parser provided by e libwww package from W3C. It requires that the libwww library from W3C is installed.
• An ISO-compatable throw/catch mechanism: It was already present in version 2.2, but now it is also documented.
• Foreign C interface now works on SGI's IRIX.
• Backtrackable assert and retract, plus Perl-style associative arrays. (Read about them in the section on modifying the database in Manual 1.)
• Oracle Interface: The Oracle interface has been brought up-to-date with newer versions of Oracle.
• ODBC Interface: The ODBC interface has been some major cleanups, and several bugs have been fixed; it also now works with SQL Server as well as Access. Support for multiple simultaneous connections has been introduced.

Backward Incompatibility

• The type bool used by the external C interface has been renamed to xsbBool, because of clashes with various include files that exist on some platforms. Likewise, the macros for dealing with the variable string type used by C programs that call XSB as a library have been renamed. For instance, vstrDEFINE is now XSB_StrDefine. See Vol. 2 of the manual for the new names.
• The predicates file_read_line, file_read_line_atom, file_read_line_list have lost the last argument (the indicator of whether the read has read the entire line). This argument is no longer necessary, since buffers expand automatically to accommodate any size input.

Version 2.2 (Tsingtao)

General

News

• Support of Attributed Variables: Attributed variables are now supported in XSB (partially compatible with SICStus 3.8). See XSB Manual, Volume 2, Attributed Variables.
• Random Number Generator: A builtin random number generator is implemented, and a set of predicates, which are compatible with SICStus 3.8, are provided.

New Packages

• libwww - a powerful Web access package. See XSB Manual, Volume 2, The Libwww Package. This package has been tested only on Solaris 2.6 and Linux 2.2. It definitely needs configuration work in order to run under Windows.
  This XSB package relies on the W3C's libwww library and requires it to be installed. The entire package is implemented in C and is much faster than other related Internet access packages for Prolog, e.g., PiLLOW). The package provides the following functionality:
  • HTML parser.
  • (Non-validating) XML parser (including handling of external entities).
  • The ability to simultaneously dispatch several HTTP requests and parse the responses as they arrive; no waiting until the entire document is received.
  • Fetching web pages and filling out forms.
  • Header information.
  • Timeouts.
  • Basic and digest authentication. SSL to follow.
  • Redirection.
  • Error handling.

Backward Incompatibility

• The C calls xsb_query_string_string and xsb_next_string that interface C programs to XSB now use the new VarString data type instead of char*. It is no longer necessary to pass the size of the buffer to these functions. See XSB Manual, Volume 2, to learn more about the variable-length string data type.

Bug Fixes

• Crashing of XSB-ODBC interface under Windows;
• Memory violations of some internal operations on delay lists.

Version 2.1 (Skol)

General

News

Process management API: XSB can now spawn subprocesses and capture their standard I/O into XSB streams. This allows XSB to communicate with other processes. See XSB Manual, Volume 2, Communication with Subprocesses.

XSB preprocessor: There is now a compiler option, xpp_on, which tells the XSB compiler to put the source through a preprocessor. The default is gpp, a powerful preprocessor that understands both C and Prolog syntax.

High-level C interface: XSB can now automatically generate wrappers for the most common C functions. Such functions can now be simply declared using compiler directives and then be called from XSB.

Enhancements to the sockets interface: New calls such as socket_set_option, socket_select,, etc. Certain socket calls and file I/O calls can be timed-out.

I/O enhancements: There are several additions to the low-level I/O library, such as file_clone, file_reopen, pipe_open. Certain socket calls and file I/O calls can be timed-out.

New section on string manipulation in manual part 2: Some of the predicates described there are old (but weren't documented) and some are new.

Call changes: New calls: number_digits/2, number_codes/2, atom_codes/2 replace atom_chars/2 and number_chars/2.

Atom length: Atom length in compiled code is no longer limited to 255. The 255 limit on the size of ldoptions directive in the Foreign C interface has been removed as well.

Debugger enhancements: Many additional options: profiling, verbose skip, extensive trace control facility.

New Packages

sModels: Implements stable model semantics.

Backward Incompatibility

• Binary incompatibility!!! The format of the XSB .O files has been changed. Make sure you recompile all your programs! (The binaries that come with the XSB distribution have the new format.)
• unix/1 is now called shell/1. It exists in module shell, and is imported from there automatically.
• The standard predicates atom_chars/2 and number_codes/2 now behave as in the Prolog standard (return lists of atoms rather than ASCII codes). The old behavior is provided by the standard predicates atom_codes/2 and number_codes/2.
• A number of backward-incompatible changes in socket calls. First, the predicates socket_send_eof/1 and socket_send_asci/2 have been removed. This functionality is available through other calls.

Second, all socket predicates now have an extra argument, the error code. The old-style predicates have been preserved, but their behavior isn't guaranteed to be 100% the same. The fileptr argument in socket_connect call has been deleted. The fileptr argument in socket_accept no longer denotes an XSB I/O port. Instead, it denoted a socket descriptor. It can be converted to an I/O port using the new builtin fd2ioport.
socket_send/3 no longer appends the message delimited (the backquote). Programs that rely on this feature will not work any longer. Instead of this old hack, socket_send now prepends a 4-byte header that specifies the length of the message body. The primitive socket_recv/3 uses it to determine the length of the message it received.

Version 2.0 (Gouden Carolus)

General

XSB Version 2.0 offers a more flexible handling of dynamic code. XSB now also includes a number of preprocessors that allow it to efficiently evaluate powerful formalisms such as F-logic, Annotated logic, and the well-founded semantics with explicit negation. Finally, XSB 2.0 provides various packages for regular expression and wildcard matching.

Large parts of XSB have been rewritten for this release, especially memory management, and representation of tabled clauses. The result is a more robust system with improved functionality that is more suitable for use in commercial and large-scale research development.

Added support for InterProlog, a Java front-end enhancement for Prolog

Packages

Version 2.0 of XSB includes the following packages:

• FLORA: A full-fledged F-logic to XSB compiler and shell.
• GAP: support for annotated logic programming.
• SLX: allows XSB to evaluate extended logic programs according to the well-founded semantics with explicit negation.
• PERLMATCH: an interface to Perl pattern matching and string substitution capabilities.
• REGMATCH: provides similar functionality, but relies on a POSIX-compliant C library instead of Perl.
• WILDMATCH: allows matching wildcards and globbing of directories. Relies on a POSIX 2 compliant C library.

Backward Incompatibility

The following incompatible changes have been made in XSB Version 2.0:

• The file .xsbrc in the home directory is no longer used. Instead, XSB now uses the directory .xsb/ and the startup file is .xsb/xsbrc It is now possible to have pretty much any Prolog code in that file.
• There is a change in how the library_directory predicate is used. The user must now assert directories into this predicate. There is no need to export this predicate (this predicate is now global).
• XSB is no longer supported on MS DOS.
• In order to be consistent with the ISO Prolog standard, XSB no longer supports mixing compiled and dynamic code for the same predicate.
• The predicate is_string/1, which used to check if its argument is a list of characters, is now replaced by the builtin is_charlist/1. There is now also is_charlist/2 (see the manual).