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https://github.com/sano-jin/lambda-gt-alpha
A reference interpreter of λGT
https://github.com/sano-jin/lambda-gt-alpha
interpreter ocaml programming-language
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A reference interpreter of λGT
- Host: GitHub
- URL: https://github.com/sano-jin/lambda-gt-alpha
- Owner: sano-jin
- License: mit
- Created: 2022-08-10T06:51:03.000Z (over 2 years ago)
- Default Branch: master
- Last Pushed: 2023-08-11T11:49:14.000Z (over 1 year ago)
- Last Synced: 2023-08-11T18:11:52.024Z (over 1 year ago)
- Topics: interpreter, ocaml, programming-language
- Language: OCaml
- Homepage:
- Size: 514 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# A Reference Interpreter of the Lambda GT Language
[](#license)
[](https://twitter.com/sano_jn)
We designed a new purely functional language, λGT,
that handles graphs as immutable, first-class data structures with
a pattern matching mechanism based on graph transformation.
Here, we implemented a reference interpreter of the language.
The interpreter is written in only about 500 lines of OCaml code.
We also have [a visualiser that runs on a browser](https://sano-jin.github.io/lambda-gt-playground/).
## Getting Started
### Prerequisites
- [opam](https://opam.ocaml.org/)
### Installation
```bash
git clone https://github.com/sano-jin/lambda-gt-alpha.git
cd lambda-gt-alpha
opam install .
dune build
```
## Usage
```bash
./run example/dlist.lgt
```
which will result in `{_Y >< _X}`.
See [/example](example) for more examples.
## Syntax
```
Expression e ::= { T } // Graph
| e1 e2 // Application
| case e1 of { T } -> e2 | otherwise -> e3 // Case Expression
| e1 + e2
| e1 * e2
| e1 - e2
// Definition (n >= 0)
| let x[_X1, ..., _Xm] x_1[_X1_1, ..., _X1_m] ... x_n[_Xn_m, ..., _Xn_m] = e1 in e2
// Recursive Definition (n >= 1)
| let rec x[_X1, ..., _Xm] x_1[_X1_1, ..., _X1_m] ... x_n[_Xn_m, ..., _Xn_m] = e1 in e2
Graph Template T ::= v (_X1, ..., _Xn) // Atom
| _X >< _Y // Fusion
| x[_X1, ..., _Xn] // Graph Context
| (T, T) // Molecule
| nu _X. T // Link Creation
Atom Name v ::= Constr // Constructor Name
| (\x[_X1, ..., _Xn]. e) // Lambda Abstraction
```
For the semantics, please see
.
We have enabled logging.
`{Log} exp` evaluates `exp`, prints the value, and returns the value; i.e., an identity function.
## Development
Please give me issues or pull requests if you find any bugs or solutions for them.
We aim to build the simplest implementation.
Thus, we may not accept a request for an enhancement.
However, we appreciate it because it will be helpful in the design and implementation
of the full-fledged language based on this PoC.
### Testing
```bash
dune runtest
```
See [test/test.ml](test/test.ml) for more information.
- Configure tests with the file.
### Directory Structures
[/bin](bin):
entry point
| File | Description |
| ---------------------- | ------------------------------------ |
| [main.ml](bin/main.ml) | Read a file and execute the program. |
[/eval](eval):
evaluator
| File | Description |
| ------------------------------------- | ---------------------------------------------------------------------------------------------- |
| [syntax.ml](eval/syntax.ml) | Syntax of atoms as an list. |
| [preprocess.ml](eval/preprocess.ml) | Transform an AST graph to a list of atoms. Alpha convert link names. |
| [eval.ml](eval/eval.ml) | The evaluator. |
| [match.ml](eval/match.ml) | Matches atoms and graph contexts and returns the obtained graph substitutions. |
| [match_atoms.ml](eval/match_atoms.ml) | Matches atoms and returns the link mappings and the rest graph. |
| [postprocess.ml](eval/postprocess.ml) | Transform the link names in the rest graphs and supply fusions according to the link mappings. |
| [match_ctxs.ml](eval/match.ml) | Matches graph contexts and returns the obtained graph substitutions. |
| [pushout.ml](eval/pushout.ml) | Substitute graph contexts with the given graph substitution (rewriting after matching). |
[/parser](parser):
lexical/syntactical analyzer
| File | Description |
| ------------------------------- | ----------------------------- |
| [syntax.ml](parser/syntax.ml) | AST definition |
| [lexer.mll](parser/lexer.mll) | Defines a token for lexing |
| [parser.mly](parser/parser.mly) | Defines a grammar for parsing |
| [parse.ml](parser/parse.ml) | Parser |
## Contact
Please feel free to contact me (ask me any questions about this).
- [twitter@sano_jn](https://twitter.com/sano_jn)
- [homepage](https://www.ueda.info.waseda.ac.jp/~sano/)
## License
MIT
[repo]: https://github.com/sano-jin/lambda-gt-alpha/tree/icgt2023/