instaparse
sci
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instaparse | sci | |
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7 | 20 | |
2,708 | 1,166 | |
- | 1.9% | |
6.0 | 7.5 | |
30 days ago | 7 days ago | |
Clojure | Clojure | |
Eclipse Public License 1.0 | Eclipse Public License 1.0 |
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instaparse
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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.
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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.
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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!
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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
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Parsing Tools
Instaparse sounds pretty close to what you're looking for assuming you're ok being limited to context-free grammars.
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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.
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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:
sci
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What's the value proposition of meta circular interpreters?
I've tried researching this myself and can't find too much. There's this project metaes which is an mci for JS, and there's the SCI module of the Clojure babashka project, but that's about it. I also saw Triska's video on mci but it was pretty theoretical.
- Sci: Configurable Clojure/Script interpreter suitable for scripting
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Windmill: Open-source developer platform to turn scripts into workflows and UIs
https://github.com/babashka/SCI if it's a requirement for proper sandboxing
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Embedding cherry in an existing CLJS app for runtime eval
Since cherry is a compiler, the code generally runs faster than with SCI which is an interpreter. For many cases SCI is fast enough, but numerical computations in a hot loop isn't one of its strenghts:
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Compiled and Interpreted Languages: Two Ways of Saying Tomato
Startup and sustained performance are absolutely implementation issues. For example, SBCL will take its sweet time to make machine code out of Common Lisp, but CLISP will interpret and generate bytecode. Both are useful, and both implement the same language. Clojure on the JVM takes also takes plenty of time to start up, so some use an interpreter instead. Furthermore neither of these languages has a cost model, so the cost of anything is an implementation issue.
- Show HN: Programming Google Flutter with Clojure
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Third party integrations with a monolithic Clojure app
So far we have relied on an increasing number of home-grown integration points to our platform, where relevant combined with the excellent SCI (so we can write some Clojure-code when adhoc data conversions / calculations / tweaking is required).
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Scala native equivalent to Clojure
Also take a look at SCI, https://github.com/babashka/sci/blob/master/doc/libsci.md
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Langdev in Clojure
You probably want to take a look at sci if you are creating a DSL or want to use Clojure itself as your DSL.
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ClojureRS – Clojure interpreter implemented in Rust
Built with the lovely SCI library (https://github.com/babashka/sci) + GraalVM, probably the most useful GraalVM project I've seen in the wild so far.
Also, Babashka will probably always support more features than ClojureRS could ever, particularly the interop with the various Java classes/functions, as that'd be very hard to achieve in ClojureRS.
What are some alternatives?
rakudo - 🦋 Rakudo – Raku on MoarVM, JVM, and JS
clojure-lsp - Clojure & ClojureScript Language Server (LSP) implementation
parser - String parser combinators
tailwindcss-typography - Beautiful typographic defaults for HTML you don't control.
chumsky - Write expressive, high-performance parsers with ease.
hotwire-rails - Use Hotwire in your Ruby on Rails app
tree-sitter-org - Org grammar for tree-sitter
mdx - Markdown for the component era
parser-combinators - Parser combinators.
rich4clojure - Practice Clojure using Interactive Programming in your editor
rosie
babashka - Native, fast starting Clojure interpreter for scripting