In Memoriam Harold Boley

A CL implementation of PSOATransRun, realizing the PSOA RuleML data and rule language.

The software required to build and run cl-psoatransrun are as follows:

• Quicklisp
• A major Common Lisp implementation (SBCL, CCL, etc.) -- one on which Quicklisp will run
• One of XSB Prolog or Scryer Prolog

Once a CL, Quicklisp and either of the two Prologs have been installed after following the instructions on their linked sites, these Quicklisp commands should be executed at the CL REPL to install the libraries on which cl-psoatransrun depends:

* (ql:quickload "drakma")
* (ql:quickload "esrap")
* (ql:quickload "pathname-utils")
* (ql:quickload "rutils")
* (ql:quickload "trivia")
* (ql:quickload "usocket")
* (ql:quickload "uiop")

Based on these libraries, cl-psoatransrun can be compiled into the Lisp image. The global variables at the top of the file prolog-engine-client.lisp, *default-scryer-prolog-path* and *default-xsb-prolog-path* must be changed to reflect the local paths of the corresponding executables on your machine. Similarly, a local copy of the PSOATransRun test suite should be downloaded, and the global variable *test-suite-directory* of psoatransrun-tests.lisp must be changed to its path.

Next, the ASDF build file "psoatransrun.asd" must be loaded into CL as in:

* (load "psoatransrun.asd")
* (asdf:load-system "psoatransrun")

(Quicklisp will have downloaded and installed the ASDF build system during its own above install, so there's no need to load ASDF explicitly via Quickload.)

The cl-psoatransrun REPL is entered with a target KB passed as a string by entering:

* (psoatransrun:psoa-load-and-repl "<target KB>")

at the CL REPL. "" must be replaced with a well-formed string representing a PSOA RuleML knowledge base with a single Assert, as in:

* (psoatransrun:psoa-load-and-repl "RuleML(
  Assert(
    _r(_p1->_v)
    _r(_p1->_f(_v))
	_o#_r(_p1->_g(_v) _p2->_f(0))
  )
)")

Translated KB:

:- use_module(standard, [local_datime/1, datime/1]).

:- auto_table.

sloterm('_26999', '_p1', '_v').
sloterm('_27000', '_p1', '_f'('_v')).
sloterm('_o', '_p2', '_f'(0)).
sloterm('_o', '_p1', '_g'('_v')).
memterm('_26999', '_r').
memterm('_27001', '_26999').
memterm('_27000', '_r').
memterm('_27002', '_27000').
memterm('_o', '_r').
>

As in the example, the RuleML KB is translated to Prolog, which is printed to the screen, and a prompt appears where RuleML queries can be entered, as in:

> _r(_p1->_f(?x))
?x=_v

psoatransrun:psoa-load-and-repl also has a keyword argument :system specifying a Prolog engine for use as a backend. Its default value is :xsb, which launches XSB Prolog at the path *default-xsb-prolog-path* as a subprocess of CL; if :system is set to :scryer, Scryer Prolog is loaded from the path *default-scryer-prolog-path*.

Support for Scryer Prolog is currently in its infancy, as Scryer is less mature than XSB and its support for tabling is less robust. For these reasons, XSB Prolog is the current default backend.

To run the above-referenced test suite, the form

* (psoatransrun-tests:run-test-suite)

is evaluated. psoatransrun-tests:run-test-suite also supports the keyword argument :system with default :xsb.

cl-psoatransrun has been tested on Linux with both Scryer and XSB as backends. It's expected to work on Linux, macOS, and other UNIX-like systems. Scryer does not yet run on Windows, although cl-psoatransrun has been tested and confirmed to work with XSB versions 3.6 and 3.8 on Windows.

Command-line options in the Java-based PSOATransRun have been reproduced in cl-psoatransrun as global variables to be set interactively from within the Lisp environment. They are listed in the table below.

cl-psoatransrun provides a few additional options not considered within the domain of the PSOA RuleML language. They are marked as N/A in the second column. Conversely, PSOATransRun options without a cl-psoatransrun counterpart are marked N/A in the first column.

All cl-psoatransrun variables are described here.