Introduction

This is the website for PProlog, a new prolog implementation written in C on and for plan 9 (9front specifically). Work started in december 2020 due to the author's need for a prolog system on 9front. It is pure experimentation and the code might be bad in more than a few places.

NOTE: There is no development currently, and it is in a kinda broken state after a failed attempt of adding modules.

Features

• A base system based on the WAM (Warren abstract machine) implemented by following the book here.
• Support for extended precision arithmetic via mp(2).
• Basic support for definite clause grammars (DCGs). For now DCG's are translated by the parser into difference lists and they do not support everything one expects.
• Lists.
• Strings represented as list of char atoms.
• The basic control predicates such as ,/2, ;/2, ->/2 and cut.
• Full unicode support.

Status

At this moment the system works OK but it has very few builtin predicates and much of what people expect from a working prolog system is still missing.

The list of builtins as of January 13, 2021 is:

• is/2
• halt/0
• consult/1
• write/1
• read/1
• call/n
• fail/0
• >/2
• ==/2
• atom/1
• integer/1
• float/1
• var/1
• compound/1
• term_variables/2

And the following predicates are implemented in the standard library:

• =/2
• \=/2
• reverse/2
• samelength/2
• append/3
• member/2
• select/3
• length/2
• nl/0
• phrase/2
• \+/2
• false/0
• true/0
• repeat/0
• once/1
• ,/2
• ;/2
• ->/2
• =\=/2

and many more all listed here.

Screenshot