Gleam JSON Parser

This is a personal project implementing a JSON parser in Gleam using parser combinators and functional programming concepts.

It's not intended as a production-ready library, but rather as a learning exercise in:

• Parser combinator techniques
• Functional programming patterns (monads, functors, applicatives)
• Gleam language features

Implementation Overview

The parser is built using a monadic parser combinator approach, with core components including:

• Parser Primitives: Basic parsers for characters, strings, and numbers
• Combinators: Higher-order parsers like many, some, or, and sep_by
• JSON Parsers: Specific parsers for JSON values (null, bool, number, string, array, object)
• Monadic Infrastructure: Implementations of pure, bind, map, and ap

The implementation demonstrates how to:

• Build complex parsers from simple ones
• Handle recursive JSON structures
• Manage parser state and error handling
• Apply functional programming patterns in a practical context

Usage

To parse a JSON file:

import gjson_parser

pub fn main() {
  gjson_parser.parse_json_file("example.json")
}

Running Tests

The project includes test cases in test/gjson_parser_test.gleam. To run them:

gleam test

passed json test suite 1

Dependencies

This project uses the standard Gleam library. No additional dependencies are required.

Motivation

Shout out to Tsoding's video which makes me want to learn parser combinators:

JSON Parser 100% From Scratch in Haskell (only 111 lines)