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https://github.com/norskeld/attolog
Minimal Prolog interpreter.
https://github.com/norskeld/attolog
fsharp interpreter prolog
Last synced: about 1 month ago
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Minimal Prolog interpreter.
- Host: GitHub
- URL: https://github.com/norskeld/attolog
- Owner: norskeld
- License: mit
- Created: 2023-10-05T21:44:05.000Z (about 1 year ago)
- Default Branch: master
- Last Pushed: 2024-09-07T20:01:30.000Z (4 months ago)
- Last Synced: 2024-09-07T21:20:32.372Z (4 months ago)
- Topics: fsharp, interpreter, prolog
- Language: F#
- Homepage:
- Size: 57.6 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Attolog
Minimal [Prolog] interpreter.
## Description
This is mostly a learning project to know more about **F#** and **Prolog**.
- [x] The implementation is rather basic. It **does not** contain cuts, arithmetic, lists, equality and so on — only basic [Horn clauses][horn-clause].
- [x] Besides the interpreter, there's a simple [hand-rolled parser combinator library](Attolog/Parser/Library.fs). Zero dependencies, yay!
## Prerequisites
You pretty much need only [.NET SDK 8.0](https://dotnet.microsoft.com/en-us/download).
## CLI
Available options:
- `-f`, `--file` A file to load before starting a REPL.
## REPL
Simply run the project:
```sh
$ dotnet run --project Attolog
```
With arguments:
```sh
$ dotnet run --project Attolog -- -f examples/sw.pl
```
### rlwrap
REPL can also be used with [rlwrap]:
```sh
$ rlwrap -a -N -t dumb dotnet run --project Attolog
```
With arguments:
```sh
$ rlwrap -a -N -t dumb dotnet run --project Attolog -- -f examples/sw.pl
```
### just
If you have [just] installed, you can use the following recipes:
```sh
$ just --list
Available recipes:
default
rl *args='' # Run Attolog with rlwrap for a slightly better experience in REPL.
run *args='' # Run Attolog with the default REPL.
```
Arguments can be passed as well:
```sh
$ just run -f examples/sw.pl
```
## Language
The language currently consists of:
- **Constants**: `x`, `y`, `constant`
- **Variables**: `X`, `Y`, `Variable`
- **Clauses**: `son(abel, adam)`, `less(X, plus(X, one))`
- **Assertions**: `son(X, Y) :- male(X), child(X, Y).`
- **Queries**: `?- child(X, vader).`
Sample program:
```prolog
% Persons.
female(leia).
male(vader).
male(luke).
male(kylo).
% Relations.
child(luke, vader).
child(leia, vader).
child(kylo, leia).
% Assertions.
son(X, Y) :- male(X), child(X, Y).
daughter(X, Y) :- female(X), child(X, Y).
grandchild(X, Z) :- child(X, Y), child(Y, Z).
% Queries (goals) can't be part of a saved program.
% ?- son(X, vader).
% ?- daughter(X, vader).
% ?- grandchild(X, vader).
```
Peano numbers (using terms to represent unary numbers, e.g. `0`, `s(0)`, `s(s(0))`, `s(s(s(0)))`, etc.):
```prolog
add(0, N, N).
add(s(N), M, s(R)) :- add(N, M, R).
% ?- add(s(0), s(0), X).
% X = s(s(0))
% ?- add(s(0), X, s(s(0))).
% X = s(0)
```
## TODO
- [ ] Get rid of exceptions, embrace errors as values.
- [ ] Refactor solver to produce values instead of effects (direct printing, reading input, etc).
## License
[MIT](LICENSE).
[prolog]: https://en.wikipedia.org/wiki/Prolog
[horn-clause]: https://en.wikipedia.org/wiki/Horn_clause
[rlwrap]: https://github.com/hanslub42/rlwrap
[just]: https://github.com/casey/just