utterances-bot commented 2 years ago

Parsing Text with Nom

Blogging, generally about Rust

https://blog.adamchalmers.com/nom-chars/

adamchalmers commented 2 years ago

I'm trying to out comments for the blog -- let me know if there's any problems.

beneyal commented 2 years ago

Very nice introduction to Nom! Thank you for posting :-)

ngwemo commented 1 year ago

I had a problem on grasping the concept of how even to use nom, but going through this blog, I've more in-depth knowledge on how and the core concepts of the crate. Thanks for effort on putting this out here man.

azzamsa commented 1 year ago

Any reason to use Nom over the other? Such Pest. I have built an app using Pest, but don't have any experience with Nom.

adamchalmers commented 1 year ago

I've been rewriting a pretty big production parser for KittyCAD into Winnow. I'll definitely be writing about Winnow soon. I think it offers some nice improvements over Nom and has a lot of potential. I found one big bug, but the maintainer fixed it within a few hours of me posting a reproduction, and released a new version. So, I'm very happy.

I haven't used grammar generators like pest before! I gave it a try once for a small project, couldn't figure it out within 20 minutes and went back to Nom. I'd like to try it again though.

On Thu, 5 Oct 2023, 10:33 pm Azzam S.A, @.***> wrote:

Any reason to use Nom over the other? Such Pest. I have built an app https://github.com/azzamsa/nai using Pest, but don't have any experience with Nom.

https://github.com/rosetta-rs/parse-rosetta-rs

nicoburns/blessed-rs#85 (comment) https://github.com/nicoburns/blessed-rs/issues/85#issuecomment-1635092972

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azzamsa commented 1 year ago

I'll definitely be writing about Winnow soon.

Can't wait to read it.

sentinel1909 commented 9 months ago

Hi Adam, I've been attempting to dive in and understand the Nom crate for about two weeks now. I thought I'd start with something simple, like parsing a sentence to look for a certain word. No matter what I try, I can't figure out how to put it all together. I understand the fundamentals (I think) about individual parsers and what they return, but I feel there is something fundamental I'm missing. The docs are lacking and, other than your blog, there just isn't much out there.

How do you iterate with Nom?

adamchalmers commented 6 months ago

Hi! You don't really iterate, there's no loops or iterators. Instead you use combinators like many1(p) which runs the p parser one or more times.

To parse a sentence I'd:

Build a parser for a single word
Run a parser like separated_list1(char(' '), word) which parses a sequence of words separated by spaces.
let's call the above parser p
Call terminated(p, char('.')) to parse a sequence of words separated by spaces, ending with a full stop.
That parser now parses a sentence!

sentinel1909 commented 6 months ago

Thanks! That helped a lot. After reading your suggestions I worked out how to parse multiple sentences with periods. Now I just have to work in other types of punctuation!

adamchalmers / blog

Parsing Text with Nom #3

Parsing Text with Nom