instaparse
nom
Our great sponsors
instaparse | nom | |
---|---|---|
7 | 85 | |
2,708 | 9,007 | |
- | 1.4% | |
6.0 | 6.5 | |
30 days ago | 5 days ago | |
Clojure | Rust | |
Eclipse Public License 1.0 | MIT License |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
instaparse
-
Chumsky, a Rust parser-combinator library with error recovery
Caveats: I've used nom in anger, chumsky hardly at all, and tree-sitter only for prototyping. I'm using it for parsing a DSL, essentially a small programming language.
The essential difference between nom/chomsky and tree-sitter is that the former are libraries for constructing parsers out of smaller parsers, whereas tree-sitter takes a grammar specification and produces a parser. This may seem small at first, but is a massive difference in practice.
As far as ergonomics go, that's a rather subjective question. On the surface, the parser combinator libraries seem easier to use. They integrate well with the the host language, so you can stay in the same environment. But this comes with a caveat: parser combinators are a functional programming pattern, and Rust is only kind of a functional language, if you treat it juuuuust right. This will make itself known when your program isn't quite right; I've seen type errors that take up an entire terminal window or more. It's also very difficult to decompose a parser into functions. In the best case, you need to write your functions to be generic over type constraints that are subtle and hard to write. (again, if you get this wrong, the errors are overwhelming) I often give up and just copy the code. I have at times believed that some of these types are impossible to write down in a program (and can only exist in the type inferencer), but I don't know if that's actually true.
deep breath
Tree-sitter's user interface is rather different. You write your grammar in a javascript internal dsl, which gets run and produces a json file, and then a code generator reads that and produces C source code (I think the codegen is now written in rust). This is a much more roundabout way of getting to a parser, but it's worth it because: (1) tree-sitter was designed for parsing programming languages while nom very clearly was not, and (2) the parsers it generates are REALLY GOOD. Tree-sitter knows operator precedence, where nom cannot do this natively (there's a PR open for the next version: https://github.com/Geal/nom/pull/1362) Tree-sitter's parsing algorithm (GLR) is tolerant to recursion patterns that will send a parser combinator library off into the weeds, unless it uses special transformations to accommodate them.
It might sound like I'm shitting on nom here, but that's not the goal. It's a fantastic piece of work, and I've gotten a lot of value from it. But it's not for parsing programming languages. Reach for nom when you want to parse a binary file or protocol.
As for chumsky: the fact that it's a parser combinator library in Rust means that it's going to be subject to a lot of the same issues as nom, fundamentally. That's why I'm targeting tree-sitter next.
There's no reason tree-sitter grammars couldn't be written in an internal DSL, perhaps in parser-combinator style (https://github.com/engelberg/instaparse does this). That could smooth over a lot of the rough edges.
-
Langdev in Clojure
Sure, you can use https://github.com/Engelberg/instaparse to create parser for any language you want, or simply create DSL in basic clojure types, like vectors.
-
Formal Specification and Programmatic Parser for Org-mode
Enter org-parser! It is indeed such a thing implemented already! Remember the magical parser I mentioned above? It is already implemented here Engelberg/instaparse too (in a Lisp)! org-parser is built on top of it by providing a formal specification for org-mode in the EBN form. Any proof that org-parser works? Indeed, there is the celebrated organice which is built on top of it. Kudos for 200ok-ch!
-
Casual Parsing in JavaScript
You might enjoy checking out Instaparse, a Clojure library. Its project page reads, “What if context-free grammars were as easy to use as regular expressions?”
It’s not over-promising, either. I went from never having heard of it before to getting complete and correct parse trees of some ancient JSP Expression Language in about 20 minutes. Most of that time was spent typing in the BNF description that I could find only in an image.
https://github.com/Engelberg/instaparse
-
Parsing Tools
Instaparse sounds pretty close to what you're looking for assuming you're ok being limited to context-free grammars.
-
I toyed with some ideas from various languages and concocted a Frankenstein which might not live for long. Come see and critique!
It is in EBNF, with some alternate conventions. It follows the syntax found in here, which I think is pretty easy to get behind.
-
Advent of Code 2020 Day 19 Monster Messages in Clojure (rest vs. next, empty sequence vs. nil)
Another way to solve it is to load the grammar directly into instaparse, specify the start rule :0 and count the successful applications of the parser to the messages:
nom
-
Planespotting with Rust: using nom to parse ADS-B messages
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.
-
Show HN: Rust nom parsing Starcraft2 Replays into Arrow for Polars data analysis
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.
-
Is this a good way to free up some memory?
Lots of people use nom for their parsing needs, but that's not the only game in town and there other options.
-
What is the state of the art for creating domain-specific languages (DSLs) with Rust?
As much as I love nom as well as other parser combinator libraries, regex-based parsers, BNF/EBNF-based parsers, etc. I always end up going back to plain old text-based char-by-char scanners.
-
What's everyone working on this week (22/2023)?
I am using nom / nom_locate to build the parser side because I've done a handful of other projects with it, and I plan to use tower-lsp to hook up the language server side.
-
Tokenizing
Look into a parsing library such as https://github.com/rust-bakery/nom
-
Something like pydantic but for just strings?
If we were in /r/learnrust I'd have recommended the nom crate for this.
- Nom: Parser Combinators Library in Rust
-
lua bytecode parser written in rust
Thanks to the flexibility of [nom](https://github.com/rust-bakery/nom), it is very easy to write your own parser in rust, read [this article](https://github.com/metaworm/luac-parser-rs/wiki/Write-custom-luac-parser) to learn how to write a luac parser
-
Should I revisit my choice to use nom?
I've been working on an assembler and right now it uses nom. While nom isn't great for error messages, good error messages will be important for this particular assembler (current code), so I've been attempting to use the methods described by Eyal Kalderon in Error recovery with parser combinators (using nom).
What are some alternatives?
rakudo - 🦋 Rakudo – Raku on MoarVM, JVM, and JS
pest - The Elegant Parser
parser - String parser combinators
lalrpop - LR(1) parser generator for Rust
chumsky - Write expressive, high-performance parsers with ease.
combine - A parser combinator library for Rust
tree-sitter-org - Org grammar for tree-sitter
pom - PEG parser combinators using operator overloading without macros.
parser-combinators - Parser combinators.
rust-peg - Parsing Expression Grammar (PEG) parser generator for Rust
rosie