https://github.com/anuraghazra/typelevel-parser
Experiment to push the limits of TypeScript's type system by writing a "real" tokenizer/parser/interpreter entirely on type-level.
https://github.com/anuraghazra/typelevel-parser
Last synced: 3 months ago
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Experiment to push the limits of TypeScript's type system by writing a "real" tokenizer/parser/interpreter entirely on type-level.
- Host: GitHub
- URL: https://github.com/anuraghazra/typelevel-parser
- Owner: anuraghazra
- Created: 2022-04-07T15:22:29.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2024-04-04T17:03:15.000Z (about 1 year ago)
- Last Synced: 2024-10-11T13:31:06.333Z (8 months ago)
- Language: TypeScript
- Size: 18.6 KB
- Stars: 143
- Watchers: 5
- Forks: 12
- Open Issues: 1
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Metadata Files:
- Readme: readme.md
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README
# What the hell is this?
This is my experiment to push the limits of TypeScript's type system by writing a "real" tokenizer/parser/interpreter entirely on type-level.
My goal was to write a DSL to query structured objects.
It's quite similar to how `lodash.get` syntax works but with a bit more flare, where you can do array index access, use `$where()` clauses & extract/filter the data from nested objects.
### Features
- Dot Access
- Array Access
- $where() clause
- Deeply nested access / chaining and all that jazz
- Support for proper syntax/parser errors
### Demo
Use [TSPlayground](https://tsplay.dev/N9EE3N)
Or clone this repo and open [demo.ts](./demo.ts) file to explore the wonders!
You can also open each of the modules separately to see how the [tokenizer](./tokenizer.ts), [parser](./parser.ts) and [interpreter](./interpreter.ts) works, I've added small demos on each time.
### Syntax
#### Dot Access
Dot access is the most basic way to access nested elements, similar to `lodash.get()`
```ts
type Demo1 = Run;
```
#### Arrays
There are two ways to access arrays,
1. Index access: where you specify which index you want eg: `comments[0]`
2. Bulk access: where you don't specify the index and thus get the whole array as union. eg: `comments[]`
```ts
type Demo1 = Run;
type Demo2 = Run;
```
#### Where clause
Using `$where()` clause you can filter out elements from array by their properties.
$where() can accept multiple comma separated value too.
```ts
type Demo1 = Run;
```
### But WHY?
Because it's fun! I love to experiment with type level code and explore ways to push the limits of the type system. I just love esoteric programming.
### Should I use this in production?
!YES
### Why even write a tokenizer/parser to do this when you can also do the same with template literal types?
Like how Haz [did here](https://twitter.com/diegohaz/status/1309489079378219009)
Because I wanted to:
- Support proper syntax errors.
- Additional complex syntaxes like $where() clause.
- Also it's fun.