https://github.com/dagit/rust-prolog
Rust implementation of prolog based on miniprolog: http://andrej.com/plzoo/html/miniprolog.html
https://github.com/dagit/rust-prolog
Last synced: 12 months ago
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Rust implementation of prolog based on miniprolog: http://andrej.com/plzoo/html/miniprolog.html
- Host: GitHub
- URL: https://github.com/dagit/rust-prolog
- Owner: dagit
- License: bsd-3-clause
- Created: 2015-10-06T04:47:30.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2020-08-28T22:22:25.000Z (almost 6 years ago)
- Last Synced: 2025-04-14T21:47:06.054Z (about 1 year ago)
- Language: Rust
- Homepage:
- Size: 99.6 KB
- Stars: 80
- Watchers: 5
- Forks: 2
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Overview
Rust implementation of prolog (originally) based on miniprolog: http://andrej.com/plzoo/html/miniprolog.html
I translated miniprolog from the above SML sources to Rust for two primary reasons:
* Firstly, I wanted a project to explore programming in Rust
* Secondly, prolog is interesting but I never felt like I properly learned it
Starting from an existing implementation was nice because it shortened the time to a working
version. The current version in this repository is very much a work in progress and overly simplistic.
I plan to improve it to better learn Rust and I plan to improve it as I learn Rust :)
In other words, this is really a playground for me to play with both Rust and prolog.
# Installation
Tested on Linux (Fedora), OSX, and Windows.
Should be as simple as: `cargo run`
# Example
```
$ cargo run
Welcome to rust-prolog!
This prolog interpreter is based on the ML code at the PLZoo:
http://andrej.com/plzoo/html/miniprolog.html
Input syntax:
?- query. Make a query.
a(t1, ..., tn). Assert an atomic proposition.
A :- B1, ..., Bn. Assert an inference rule.
$quit Exit interpreter.
$use "filename" Execute commands from a file.
Prolog> $use "src/likes.pl"
Prolog> ?- likes(X,Y).
Y = mary
X = john
more? (y/n) [y]
```
# Roadmap
I haven't figured out exactly which directions I want to take this in, but some
ideas I've been kicking around include:
* [ ] Add a [type system](http://www.cs.bham.ac.uk/~udr/papers/TypedProlog.pdf)
* [ ] Add constraints and constraint checker.
* [ ] Add a bottom-up search procedure (perhaps even replace the existing
top-down search procedure entirely).
* [ ] Add program transformations to generate more efficient queries (for
instance, magic sets and entailment elimination).
* [ ] Change the syntax to one that supports mixfix declarations.
Completed:
* [x] Change the search procedure to a [complete search](http://www.ai.sri.com/~stickel/pttp.html).
This is now done. It uses iterative deepening with an admissable heuristic
that does a lower bound estimate on the number of unifications required to
solve the current goal. It also generates contrapositives (instead of using
restarts).
* [x] Add more primitive types, lists, numbers, etc and make a small standard library.
* [x] Improve the garbage collection. Currently cycles are allowed but due to
the hash consing, nothing is ever collected. A simple scheme that should
allow some collection is to throw away terms generated by unification
and terms that are part of a query after the query has terminated. This
should lend itself to a simplistic form of regions.
Old goals that I may not pursue after all:
* [ ] Compile to the [Warren Abstract Machine](http://wambook.sourceforge.net/).
The reason I've reconsidered this one is because my search procedure is
slowing moving towards a more general constraint logic search procedure. The
WAM is still rather elegant and I may follow the development at some point
and see if I can adapt it to fit the general CPL algorithm. Perhaps someone
else has already done this work.