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Qu-Prolog is an extended Prolog designed primarily as a prototyping language and tactic language for interactive theorem provers. It is the implementation language for the Ergo theorem prover.

Qu-Prolog provides support for symbolic computation on notations which appear in mathematics and in specification languages such as Z. Highlights include support for arbitrary quantifiers with parallel bindings and optional typing information, and support for higher-order notations such as function-valued expressions. The unification algorithm is correspondingly extended to support these features.

Qu-Prolog is multi-threaded and provided high-level communication between threads, processes and machines.Together, these features provide a simple, yet powerful mechanism for agent programming.

Distinctive features of Qu-Prolog include:

  • a separate type of Prolog variable to represent object-level variables;
  • support for quantified terms;
  • notations for substitution application;
  • an implicit parameter mechanism --- a modal logic programming capability whose practical effect is to provide a form of backtrackable assignment;
  • support for efficient higher-order programming;
  • support for logic programming of interactive applications by enabling query processing to extend across multiple queries (implemented as variants of read and write that provide access to Prolog variables across multiple input and output events);
  • management of goal delays;
  • multiple threads;
  • high-level symbolic communication between threads, processes and machines in a uniform way;
  • a heap garbage collector;
  • a dynamic database garbage collector; and
  • indexing on the dynamic database.

Qu-Prolog Terms

Assuming all and lambda has been declared as a quantifier (e.g. op(500, quant, all)) and x and y have been declared as object variable prefixes (e.g. obvar_prefix([x,y]) ) then the following are valid Qu-Prolog terms.

  • all x A - a quantified term whose quantifier is all, whose bound variable is x, and whose body is A .
  • all x:nats A - same as above but with a term attached to the bound variable - typically used to add types.
  • all [x:nats, y:nats] A - same as above but with a parallel binding for two object variables.
  • !!integral(A,B) x f(x) - a quantified term whose quantifer is not a declared atom (the !! is a quantifier escape).
  • [A/x, B/y]C - a substitution term - all free occurrences of x and y in C are respectively replaced by A and B.
  • (lambda x A)(B) - a compound term whose functor is a quantified term.
  • F(A) - a compound term whose functor is a variable.

Delayed Goals

Any goal can be delayed using delay_until/2 and Qu-Prolog can generate both unification delays and not-free-in delays during unification. Users can access the delays with get_delays/1.

Threads

A thread is created with the goal thread_fork(ThreadID, ThreadGoal) that starts executing the goal ThreadGoal in a new thread named ThreadID. Threads are controlled with calls to predicates such as thread_yield, thread_sleep, thread_wait_on_goal and thread_kill.

Communication

Qu-Prolog uses the Pedro subscription/notification server for interprocess communication. Qu-Prolog threads can subscribe to messages of a particular pattern and send notifications.

Pedro also provides peer-to-peer messages and so Qu-Prolog threads can communicate using symbolic addresses that are similar to email addresses. The following are examples of the use of symbolic peer-to-peer communication.

  • Term ->> ThreadID - sends Term to the thread named ThreadID on the same process.
  • Term ->> ThreadID:ProcessName - same as above but sent to a thread on the named process.
  • Term ->> ThreadID:ProcessName@MachineAddress - same as above but sent to the given machine.
  • Term <<- Address - read the next message from the message buffer.
  • Term <<= Address - search the message buffer for a message that unifies with Term and whose address unifies with Address
There is also a message_choice predicate that provides powerful message buffer searching.

Examples

Manuals

  • The Qu-Prolog 10.7 reference manual: main.pdf (560K) and html MAIN.html (central page is 250K)

Downloads

Qu-Prolog runs on Unix and Linux machines. The release comes with the above manuals and example programs.

New Release: Qu-Prolog 10.8 Date:14/5/23
  • The same as 10.7 - fixed the corruption of the 10.7 release.

Download Qu-Prolog 10.7: Qu-Prolog 10.8 (2Mbytes)
Download Qu-Prolog for Windows installer (using the 10.7 installer): QuProlog_setup10.7.exe (3Mbytes)

Release: Qu-Prolog 10.7 Date:30/5/22
  • Upgrade to the latest pcre2 regular expression library (specifically libpcre2-8)
  • Fix bug in multifile
  • Remove characters beteen '.' and EOL in a query in the interpreter.

Corrupted release removed. (2Mbytes)
Download Qu-Prolog for Windows installer: QuProlog_setup10.7.exe (3Mbytes)

Release: Qu-Prolog 10.6 Date:30/06/20
  • coverts Pedro messages on read and write betwwen zero arity compounds and a special 1-arg compound - for better management of messages in Qulog.
  • modernize configure - remove explicit dependency on gcc

Download Qu-Prolog 10.6: Qu-Prolog 10.6 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog_setup10.6.exe

Release: Qu-Prolog 10.5 Date:29/12/19
  • fix bug in setarg for lists

Download Qu-Prolog 10.5: Qu-Prolog 10.5 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog_setup10.5.exe

Release: Qu-Prolog 10.4 Date:25/11/19
  • fix bug in pedro parser
  • update windows install

Download Qu-Prolog 10.4: Qu-Prolog 10.4 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog_setup10.4.exe

Release: Qu-Prolog 10.3 Date:06/09/19
  • file_directory_name and file_base_name added.
  • Fix for tokenizing floats on ARM machines.

Download Qu-Prolog 10.3: Qu-Prolog 10.3 (1Mbytes)

Release: Qu-Prolog 10.2 Date:08/03/19
  • Regular expression support has been added - to use you need to have installed pcre2 before building QuProlog.
  • Minor fixes related to 32bit machines and Windows

Download Qu-Prolog 10.2: Qu-Prolog 10.2 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog10.2_setup.exe

Release: Qu-Prolog 10.1 Date:16/05/18
  • Regular expression support added (re match)
  • Minor fixes

Download Qu-Prolog 10.1: Qu-Prolog 10.1 (1Mbytes)

Release: Qu-Prolog 10.0 Date:07/06/16
  • Open sourced
  • Minor fixes

Download Qu-Prolog 10.0: Qu-Prolog 10.0 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog10.0_setup.exe

Release: Qu-Prolog 9.7 Date:10/12/15
  • Minor fixes

Download Qu-Prolog 9.7: Qu-Prolog 9.7 (1Mbytes)

Release: Qu-Prolog 9.6 Date:12/05/15
  • Added better support for writing strings

Download Qu-Prolog 9.6: Qu-Prolog 9.6 (1Mbytes)

Release: Qu-Prolog 9.5 Date:13/10/14
  • Minor modifications and bug fixes.

Download Qu-Prolog 9.5: Qu-Prolog 9.5 (1Mbytes)

Release: Qu-Prolog 9.1 Date:23/08/11
  • Slight modification to better support Pedro 1.9 for communications.

Download Qu-Prolog 9.1: Qu-Prolog 9.1 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog9.1_setup.exe

Release: Qu-Prolog 9.0 Date:14/07/11
  • Qu-Prolog ported to Windows (at last!)
  • Bug fixes + minor improvements

Download Qu-Prolog 9.0: Qu-Prolog 9.0 (1Mbytes)
Download Qu-Prolog for Windows installer: QuProlog_setup.exe

Release: Qu-Prolog 8.12 Date:24/11/10
  • Added timers - see create_timer in manual.
  • Added gettimeofday - get time as a float.
  • Added absolute_file_name - file expansion.
  • Compiler can now cope with spaces in filename.
  • Command line editing/history/completion added (using rlwrap).
  • Bug fixes + minor improvements
Thanks again to Paulo Moura for various suggestions and bug reports.

Download Qu-Prolog 8.12: Qu-Prolog 8.12 (1Mbytes)

Release: Qu-Prolog 8.11 Date:18/06/10
NOTE:Qu-Prolog 8.11 requires Pedro 1.5 or greater for communications because of the change of connection protocol.
  • Added two different timers to thread_wait_on_goal. One will cause the call to fail after a given timeout if it hasn't already succeeded. The other rechecks the goal at least as often as the specified timeout.
  • Changed protocol for Pedro connections in order to better determine machine names in a variety of network setups.
  • improving ISO compatibility
  • bug fixes
Thanks to Paulo Moura for various suggestions and bug reports.

Download Qu-Prolog 8.11: Qu-Prolog 8.11 (1Mbytes)

Release: Qu-Prolog 8.10 Date:01/12/09

  • Port to 64bit
  • setup_call_cleanup added
  • bug fixes
(Thanks to Rhys Weatherley for suggestions for the 64 bit port and to Ulrich Neumerkel for help with setup_call_cleanup and other suggestions.)

Download Qu-Prolog 8.10: Qu-Prolog 8.10 (1Mbytes)

Release: Qu-Prolog 8.9

  • Minor improvements in efficiency
  • CHR (Constraint Handling Rules) added

Download Qu-Prolog 8.9: Qu-Prolog 8.9 (1Mbytes)
Release: Qu-Prolog 8.8

  • Improved efficiency for object trail
  • ip_array_get_entries added

Download Qu-Prolog 8.8: Qu-Prolog 8.8 (1Mbytes)

Release: Qu-Prolog 8.7

  • Fix compiler bug

Download Qu-Prolog 8.7: Qu-Prolog 8.7 (1Mbytes)
Release: Qu-Prolog 8.6

  • Fix make clean
  • Fix string escape bug

Download Qu-Prolog 8.6: Qu-Prolog 8.6 (1Mbytes)
Release: Qu-Prolog 8.5

  • Uses new pedro connection protocol - needs at least pedro-0.8
  • More efficient lookup of IP address and machine name.

Download Qu-Prolog 8.5: Qu-Prolog 8.5 (1Mbytes)
Release: Qu-Prolog 8.3

  • bug fix in messages

Download Qu-Prolog 8.3: Qu-Prolog 8.3 (1Mbytes)
Release: Qu-Prolog 8.2

  • bug fix in message_choice

Download Qu-Prolog 8.2: Qu-Prolog 8.2 (1Mbytes)
Release: Qu-Prolog 8.1

New features:
  • -g initial-goal option added to the interpreter - initial-goal is executed before the interpreter starts.

Download Qu-Prolog 8.1: Qu-Prolog 8.1 (1Mbytes)
Release: Qu-Prolog 8.0

New features:
  • Elvin and ICM communication has been replaced by Pedro communication.

Download Qu-Prolog 8.0: Qu-Prolog 8.0 (1Mbytes)
Release: Qu-Prolog 7.4

New features:
  • Strings added.

Download Qu-Prolog 7.4: Qu-Prolog 7.4 (1Mbytes)
Release: Qu-Prolog 7.2

New features:
  • Bugs fixed.
  • icm_connected and icm_ping added

Download Qu-Prolog 7.2: Qu-Prolog 7.2 (1Mbytes)
Release: Qu-Prolog 7.1

New features:
  • Bugs for MACOSX users fixed.
  • Hash table added.

Download Qu-Prolog 7.1: Qu-Prolog 7.1 (1Mbytes)
Release: Qu-Prolog 7.0

New features:
  • Floating point numbers added (finally!).
  • Extension to thread_wait_on_goal to allow waits on specific predicates

Download Qu-Prolog 7.0: Qu-Prolog 7.0 (1Mbytes)
Release: Qu-Prolog 6.7

New features:
  • The use of Qu-Prolog terms in Elvin subscriptions added.
  • Some minor problems fixed

Download Qu-Prolog 6.7: Qu-Prolog 6.7 (1Mbytes)
Release: Qu-Prolog 6.5

New features:
  • QT GUI added - provides GUI support for MacOSX users (and an alternative for Linux users).
  • Some minor problems with make files fixed

Download Qu-Prolog 6.5: Qu-Prolog 6.5 (1Mbytes)
Release: Qu-Prolog 6.4

New features:
  • Elvin discovery added
  • increased compatibility with ISO standard
  • predicates declared as dynamic that appear in a file being compiled are compiled as dymamic predicates rather than producing an error message
  • some bug fixes
(Thanks to Paulo Moura for suggestions and bug reports.)

Download Qu-Prolog 6.4: Qu-Prolog 6.4 (1Mbytes)
Release: Qu-Prolog 6.3

New features:
  • Elvin subscription/notification communication added.
Download Qu-Prolog 6.3: Qu-Prolog 6.3 (1Mbytes)

Release: Qu-Prolog 6.2
New features:
  • better use of C++ standard classes - now compiles under gcc 3 compilers.
  • simplified thread scheduler and thread blocking management.
  • reworking of message classes - by providing a message base class we are now better able to support other communication models (such as Elvin).
Apart from the modified Tcl/Tk interpreter, Qu-Prolog 6.2 will run on MacOSX - see the INSTALL file for details.

Download Qu-Prolog 6.2: Qu-Prolog 6.2 (1Mbytes)

For more information about Qu-Prolog, contact the Peter Robinson at: pjr@itee.uq.edu.au.

Feedback on any aspect is also welcome.




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