About AZ-Prolog

AZ-Prolog is a general-purpose implementation of the Prolog programming language developed for directly running the Prolog-KABA source code, which was widely used in 1980s, and for enabling to build stand-alone applications when fully compiled. The initial version was made available for OS/2 and UNIX and first shipped in 1989.

Since its first release, AZ-Prolog, while based on Prolog’s language specification, has been constantly updated and enhanced with various features and extended predicates being added, so that the product enables developers to build truly useful applications that will meet the needs of the times.

AZ-Prolog is the world’s fastest, ISO/DEC-10 Prolog compatible implementation of the Prolog logic programming language.

AZ-Prolog also provides an interpreter to use for easily executing and debugging programs; a bytecode compiler to improve interpreter performance; a C-compiler to create even faster stand-alone executable programs; and a CGI interpreter that enables to publish programs as websites.

AZ-Prolog is now available for 64-bit operating systems. This means that it can use the huge address space provided by 64-bit architectures, enabling to handle much larger and more complex programs, which was never possible before.

In addition, a parallel computing framework similar to MPI (Message Passing Interface) has been deployed to take full advantage of multicore processors, resulting in faster execution of Prolog programs.

Furthermore AZ-Prolog offers a variety of add-ons including those to support constraint logic programming as well as socket programming, enabling to develop a broader range of applications.

For Version 9 and later, feature structures are used for easy implementation of unification grammars such as HPSG.

Typed feature structures will soon be implemented.


System Requirements

Operating systems Win32/64(Windows 10/8/7)
Linux 32/64 (Ubuntu 16.04/14.04/12.04)
Mac OS(v10.12 Sierra)、Mac OS X(v10.9 Mavericks, v10.10 Yosemite, v10.11 El Capitan)
C-compilers Microsoft Visual C++ 2013 Express Edition and GCC
Hardware Hardware environment capable of running the above operating systems
Hardware environment capable of running the above operating
Disk space 60MB or greater


  • The 32-bit versions of AZ-Prolog run on 64-bit operating systems, but the 64-bit versions do not run on 32-bit operating systems. Some add-ons (including Cabocha) use external libraries, and therefore, they are compatible only with the 32-bit versions.
  • For the Mac versions, only OSX Mavericks v10.9 and/or later are officially supported. No performance guarantee shall apply when used with earlier versions.


Key differences between 32-bit and 64-bit versions

  32-bit version 64-bit version
Cell size 8byte 16byte
The range of integer values -2147483648 to 2147483647 -9223372036854775808
to 9223372036854775807
Arithmetic operations See below
Numeric array 1,2,4byte 1,2,4,8byte
Maximum stack/heap size Total of 2GB Determined by OS and RAM


  • The second and third arguments of e_register/3 and the first argument of repeat/1 will also be integer values in the same range.
  • Arithmetic operations involving both integers and floating point numbers (double precision) result in floating point numbers. However, the range of integers is larger than that of mantissa part of floating point numbers (52 bits), and as a result, arithmetic operations involving very large integers can lead to the loss of trailing digits.