percival
nom
percival | nom | |
---|---|---|
12 | 85 | |
571 | 9,020 | |
- | 0.9% | |
0.0 | 7.4 | |
about 1 year ago | 9 days ago | |
Rust | Rust | |
MIT License | MIT License |
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percival
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Learn Datalog Today
Souffle and Cozo mentioned below already implement the whole of "traditional" datalog.
Percival (https://github.com/ekzhang/percival) has some very nice examples showing how you can interactively write and test rules on top of a datalog interpreter.
Bud (http://bloom-lang.net/bud/) is Hellerstein's proof of concept playground. It has bit-rotted in the past few years, but the examples are readable even if you can't easily get it working.
The complexity can be quite good. You can syntactically determine when you've written linear recursion (equivalent to a for loop) vs not. Otherwise, the complexity is what you'd expect from incremental view maintenance in a normal SQL database. Which is to say O(n^k) with k being the number of relations joined, but usually much, much less with appropriate indexes and skew in the data. All the usual tricks concerning data normalization and indexes from databases apply.
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Soufflé: A Datalog Synthesis Tool for Static Analysis
I've worked on percival a bit, it compiles (transpiles?) the datalog ast into javascript code on demand and executes it to get the results, see [1]. Percival's creator, Eric, also submitted a 10m presentation about the project [2] to the HYTRADBOI 'virtual conference' earlier this year [2]. They also submitted a Show HN that received a couple comments [3]. The Have You Tried Rubbing A Database On It conference included several awesome presentations featuring datalog, which readers may find interesting [4].
[1]: https://github.com/ekzhang/percival/blob/main/crates/perciva...
[2]: https://www.hytradboi.com/2022/percival-a-reactive-language-...
[3]: https://news.ycombinator.com/item?id=29521975
[4]: https://www.hytradboi.com/
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Chumsky, a Rust parser-combinator library with error recovery
I haven't written a parser with Chumsky, bit I've played with a little one a bit if you wanna see an example syntax. The error reporting for this project is implemented with `ariadne` which is also really slick.
Parser: https://github.com/ekzhang/percival/blob/main/crates/perciva...
Error reporting: https://github.com/ekzhang/percival/blob/main/crates/perciva...
Datalog playground: https://percival.ink/
To see an error report, delete some punctuation from one of the Datalog code blocks then press shift-return.
- Show HN: Percival – Web-based reactive Datalog notebooks, made with Rust+Svelte
- Percival: Web-based, reactive Datalog notebooks for data analysis and visualization, written in Rust and Svelte
nom
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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.
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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.
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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.
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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.
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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.
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Tokenizing
Look into a parsing library such as https://github.com/rust-bakery/nom
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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
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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
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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?
codeql - CodeQL: the libraries and queries that power security researchers around the world, as well as code scanning in GitHub Advanced Security
pest - The Elegant Parser
crepe - Datalog compiler embedded in Rust as a procedural macro
lalrpop - LR(1) parser generator for Rust
modus - A language for building Docker/OCI container images
combine - A parser combinator library for Rust
cclyzerpp - cclyzer++ is a precise and scalable pointer analysis for LLVM code.
pom - PEG parser combinators using operator overloading without macros.
souffle - Soufflé is a variant of Datalog for tool designers crafting analyses in Horn clauses. Soufflé synthesizes a native parallel C++ program from a logic specification.
rust-peg - Parsing Expression Grammar (PEG) parser generator for Rust
async-observable - Async & reactive synchronization model to keep multiple async tasks / threads partially synchronized.
chumsky - Write expressive, high-performance parsers with ease.