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https://github.com/davidelettieri/sample-racket-language
Minimal setup to create a new racket language with custom syntax
https://github.com/davidelettieri/sample-racket-language
programming-languages racket racket-language
Last synced: 23 days ago
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Minimal setup to create a new racket language with custom syntax
- Host: GitHub
- URL: https://github.com/davidelettieri/sample-racket-language
- Owner: davidelettieri
- License: mit
- Created: 2023-02-21T17:19:22.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2024-11-26T07:21:46.000Z (3 months ago)
- Last Synced: 2024-11-26T08:19:31.940Z (3 months ago)
- Topics: programming-languages, racket, racket-language
- Language: Racket
- Homepage:
- Size: 35.2 KB
- Stars: 2
- Watchers: 2
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
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# Minimal setup for a racket language with custom syntax
This repo serves as a start project for a new racket language with a custom surface syntax. A parser generator is used to parse a very simple language of aritmetic expression only integers, `+`, `-` and grouping `(..)`. Our sample language supports multiple aritmetic expressions defined on different lines.
Valid expressions in the language are:
```
1+2-(10-2)
```
and
```
4-5
```
and
```
1+2
6+7+9
```
but not
```
1.5-1
```
# How to use it
Run in the root directory of the project
```bash
raco pkg install
```
After that you will be able to use
```
#lang sample-racket-language
```
at the top of your racket files. The `use-language.rkt` file contains a minimal example using the language defined in the repo.
Please note that the language name `sample-racket-language` is defined into the `info.rkt` file with the syntax
```scheme
(define collection "sample-racket-language")
```
The folder structure has been created using
```bash
raco pkg new sample-racket-language
```
and then customizing the collection name.
## Running the test suite
```
raco test -x -p sample-racket-language
```
## How it works
The project leverages the [parser-tools-lib](https://pkgs.racket-lang.org/package/parser-tools-lib) package to create a parser for the sample language.
The language project is built around three files:
- `lexer.rkt`
- `parser.rkt`
- `main.rkt`
In the `lexer.rkt` file we define the tokens of the language differentiating between tokens that are carrying a value with them (for example number literals), using `define-tokens`, and tokens that have no value (for example parenthesis), using `define-empty-tokens`.
In the `parser.rkt` we use the tokens defined in the `lexer.rkt` file to define our parser. The parser will return a tree describing the expression using custom functions `add`,`multiply`,`subtract`,`divide` where by custom I mean that racket doesn't provide functions nor macros with these names by default.
The `main.rkt` contains the required macros, the required exports and brings everything together defining the language module with a reader submodule.
```scheme
(module reader racket
...)
```
where we provide the `read` and `read-syntax` functions as required when creating a language with a custom surface syntax. The module definition part is sourced from the [racket official documentation](https://docs.racket-lang.org/guide/language-collection.html).
# Resources
[This](https://school.racket-lang.org/2019/plan/index.html) is an awesome resource about macros and languages.