nom VS rust-peg

And on a related note, this project was for educational purposes, but if the author wants to do more parsing in Rust, there's the excellent `nom` crate [1], which provides a JSON parser as an example [2].

It uses a very similar paradigm to what the author used in the article, and provides a lot of helper utilities. I used it to parse a (very, very small) subset of Markdown recently [3] and enjoyed the experience.

[1] https://github.com/rust-bakery/nom

[2] https://github.com/rust-bakery/nom/blob/main/examples/json.r...

[3] https://git.sr.ht/~bsprague/logseq-to-linkwarden

To see these concepts in action, check out my repository Fun with Nom. It’s a project where I explored the Nom crate during a deep dive early in 2024.

Part of that inspiration was learning about parser combinators, particularly Rust's nom library. Of course, parser combinators - particularly in Rust - presented a bit of a learning curve. But this incredible post by Bodil Stokke really helped me understand how they worked, and made me feel empowered. In fact, for small DSLs, I often use parser combinators - for instance, with ts-parsec in TypeScript and parsy in Python. If you want to dip your toes in and have a head for functional programming DSLs, this is a great direction to go in.

Unlike the previous parser, which was based on the nom parser-combinator library, the new parser is an optimised recursive descent parser with a separate lexing step. This change allows for more efficient parsing by separating the tokenisation of the input from the parsing logic itself, streamlining the parsing process.

Just in case you are not familiar with nom, it is a parser combinator written in Rust. The most basic thing you can do with it is import one of its parsing functions, give it some byte or string input and then get a Result as output with the parsed value and the rest of the input or an error if the parser failed. tag for example is used to recognize literal character/byte sequences.

I may be the only one not familiar, but nom refers to https://github.com/rust-bakery/nom which looks like a pretty handy way to parse binary data in Rust.

Lots of people use nom for their parsing needs, but that's not the only game in town and there other options.

And some related parser tools: - https://github.com/kevinmehall/rust-peg - https://github.com/pest-parser/pest - https://github.com/lalrpop/lalrpop

Rust is a very nice langage for implementing compilers, and has a nice ecosystem for it (logos, rust-peg, lalrpop, astmaker -- this one is mine --, etc...).

My peg crate is a parser generator that supports arbitrary token types as input. See https://github.com/kevinmehall/rust-peg/blob/master/tests/run-pass/tokens.rs for an example.

The one rust parser-generator I used is PEG

The two parser generators that I am aware of are lalrpop and PEG. There both great, and have seen some use by languages that have been written in Rust.

rust-peg

I wanted to create a parser for Apertium Stream. In 2014, I used Whittle in Ruby. If this year were 2001, I would use Lex/Yacc. Anyway, this year is 2021. I wanted to create this parser in Rust. I tried to find what is similar to Lex/Yacc. I found Rust-Peg. I found a link to Nom from Rust-Peg's document. My first impression was Nom example is easy to read. At least, its document claimed Nom is fast.

The peg crate has a resolved issue about this.

I don't really know that much about parsing and grammars, other than what I've learned about regular languages and expressions and context-free languages in a standard Theory of Comp course from my university. I basically just learned peg by reading the Wikipedia article on PEGs, reading the crate documentation to understand the syntax, and then looking at some of the peg examples on their GitHub to understand how it works in practice.