frontpage.
newsnewestaskshowjobs

Open Source @Github

fp.

Open in hackernews

LSP client in Clojure in 200 lines of code

https://vlaaad.github.io/lsp-client-in-200-lines-of-code
164•vlaaad•1y ago

Comments

whalesalad•1y ago
This is the most Java-y Clojure I’ve probably ever read. Just use Java? It’s so verbose and complex for what it is doing. Breaking this down into smaller functions and using core.async would make it even more succinct.

Just want to emphasize this because clojure is indeed a small, lesser known language that has a hard enough time attracting users. This is not what anyone would consider an idiomatic example of using clojure.

roenxi•1y ago
Would it be 200 lines of Java? It'd be 200 lines of just for the boilerplate. It isn't really a selling point of Clojure because it is subjective, but low-syntax high-terseness look of the code is in itself a reward for using the language.

And there isn't anything especially wrong with sticking to Java primitives if someone is comfortable with them. They work fine for Java programmers. The dude doesn't need to learn a new async library to write an LSP client if he doesn't feel like it. Code works, its easy to read, easy to understand and modify.

koito17•1y ago
Line count is not very useful to compare without the context of standard library size, third-party dependencies, etc. The code in TFA depends[1] on a JSON library[2] that is about a thousand lines of code (excluding tests) wrapping a Java library for JSON decoding.

Then there's other things to consider, like the fact that this LSP client, while succinct, pays not only the cost of loading Jackson, but also the cost of loading clojure.core, which is quite non-trivial[3]. Startup time for LSP servers and clients definitely matters to some, considering that e.g. even clojure-lsp recommends running native executables over JAR files[4]. Can't find documentation proving it's for quick startup, but it's a plausible rationale for their recommendation of a binary over a JAR.

Note: I have used Clojure professionally and in hobby projects. I think it's nice that one can interactively develop a minimal LSP client and the resulting amount of work is roughly 200 lines of code. I say "minimal" because it's unclear how this client deals with offsets reported by LSP servers, which are all given as offsets in a UTF-16 encoded string. In any case, I still think advertising "LSP client in 200 lines of code" hides valuable information regarding functionality, implementation, "actual" code size, and trade-offs made in the choice of technology stack.

[1] https://github.com/vlaaad/lsp-clj-client/blob/a567e66/deps.e...

[2] https://github.com/metosin/jsonista/blob/c8f2b62/project.clj...

[3] https://clojure-goes-fast.com/blog/clojures-slow-start/#cloj...

[4] https://clojure-lsp.io/installation/#embedded-jar-legacy-exe...

pron•1y ago
Between records and compact classes [1] Java's boilerplate isn't what it once was.

[1]: https://openjdk.org/jeps/512

newlisp•1y ago
It's idiomatic "low-level" Clojure, though. Not everything is a happy place where you're just manipulating maps and vectors like in most examples.
0x1ceb00da•1y ago
> lesser known language that has a hard enough time attracting users

For very good reasons.

dig1•1y ago
I don't see why this wouldn't be considered idiomatic clojure code; it makes proper use of all the facilities provided by the language and the main intention of this code is to follow the article. Additionally, the clojure core team often encourages not to shy away from using java code directly, as this approach strikes a good balance between performance and language expressivity.

> It’s so verbose and complex for what it is doing. ... and using core.async

I think this code is actually quite straightforward and easy for a clojure developer to understand. In fact, using core.async in this case would be overkill and could complicate things further.

daveliepmann•1y ago
This looks like the other completely normal, idiomatic Clojure programs I've seen which manipulate a StringBuilder. And as Clojurians go I'm far to the succinctness/concision-preferring end of the spectrum.

I'm curious to see your core.async-based version :)

askonomm•1y ago
Holy crap is this unreadable or what (notably the lsp-base fn). There's a reason why in most Clojure companies I've worked at we try to make as small functions as possible, because otherwise it very very quickly becomes an unreadable mess, and you write code after all for humans to read, because if you didn't, you might as well just write binary. But, I'm not surprised many people don't want to get into Clojure or Lisps in general, because it takes a boatload of conventions and active discipline to make it a good experience.
slifin•1y ago
To me something unreadable is code that I cannot statically make any assertions about the runtime behaviour of the code

This function you're complaining about looks like 2 virtual threads doing program input reading and output writing for the LSP client given some ArrayBlockingQueues in about 25-30 lines

If I wanted the complete story I could use Clojure's inbuilt test runner to slip some ArrayBlockingQueues in there and run it under record with Flowstorm

Then leisurely seek through the entire state of the program, to get the play-by-play of how this works

There are so many good design choices in this language and a good 30% of colleagues I run into are not even doing the basics of like running a REPL, I think some people just need to clock in with a decade of C# or PHP or TS or JS or Python or whatever to get a taste of a language with next to no inbuilt immutability, statements instead of expressions, no reload-ability in the language semantics and just crapshot debuggers that run in lockstep with the program execution

Mossad accicentally injected data to a French lawyer phone instead of extracting

1•0x54MUR41•3m ago•0 comments

Show HN: CIRadar – Self-hosted CI failure diagnosis

https://github.com/Bluezly/CIRadar
1•bluezly•4m ago•0 comments

Chattjb.org is a real human behind the scenes

https://twitter.com/CatJova/status/2085467412259106993
1•arnonejoe•4m ago•0 comments

Provenance

https://en.wikipedia.org/wiki/Provenance
1•soupspaces•5m ago•0 comments

Zig's Io.Threaded Is Neat

https://matklad.github.io/2026/08/06/neat-io-threaded.html
1•Retro_Dev•10m ago•0 comments

Never Gonna Give You Up but the lyrics are in alphabetical order [video]

https://www.youtube.com/watch?v=Svj1bZz2mXw
1•mooreds•12m ago•0 comments

One Cut – Edit Video by Editing Code

https://github.com/smy20011/onecut
1•smy20011•13m ago•0 comments

See the Sun like never before with most detailed images yet

https://www.bbc.com/news/articles/c36d4376nd2o
2•mooreds•14m ago•0 comments

Some software talks I like

https://char.lt/blog/2026/08/talks-i-like/
1•vinhnx•14m ago•0 comments

LA Freeway (Long's to Arapaho Traverse)

https://www.mountainproject.com/route/117783697/la-freeway-longs-to-arapaho-traverse
1•mooreds•15m ago•0 comments

E.U. Nears Approval of Gene-Edited Crops as Olive Sector Eyes Applications

https://www.oliveoiltimes.com/world/e-u-nears-approval-of-gene-edited-crops-as-olive-sector-eyes-...
2•johntfella•18m ago•0 comments

MRMS Renderer – Open-Source NOAA MRMS Radar Renderer for Python

https://github.com/Taylor-Creative-Development/mrms-renderer
1•davidtaylorjr•19m ago•0 comments

Show HN: Qwen3.8-Max – Use Qwen Studio and MCP to Code Locally for Free

https://github.com/tohid4n/qwen3.8-max-local-coding
1•tohid4n•20m ago•0 comments

Retraction: The App Store Rejection of the Week That Was a Correct Rejection

https://daringfireball.net/2026/08/retraction_app_store_rejection_of_the_week
4•minimaxir•22m ago•0 comments

Ms. Tippi Hedren – The Godmother of the Vietnamese Nail Industry

https://vietnamesemuseum.org/details/ms-tippi-hedren/
2•thunderbong•24m ago•0 comments

Alternate Routing Graph

https://agentchannels.org/
1•FelineStateMach•25m ago•0 comments

The Color Recession May Be Permanent

https://www.theatlantic.com/ideas/2026/08/colorless-gray-products-houses/688174/
1•fortran77•25m ago•0 comments

DragonRuby Jam License – Free to All

https://dragonruby.itch.io/dragonruby-gtk/devlog/1620970/dragonruby-jam-license-free-to-all
1•amirrajan•26m ago•0 comments

I asked 4 AI companions what they were. They lied, then texted me the next day

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=7244220
2•Ai_Sycophancy•27m ago•0 comments

Real-time MCP interceptor that blocks .env reads and dangerous commands agents

https://marketnow.site/
2•eddyflores•35m ago•0 comments

Show HN: Pomona, offline small AI reasoners for agricultural sensors

https://github.com/okyanu/pomona
1•okyanu•37m ago•0 comments

Open Discovery Loop

https://opendl.ai/
1•arionhardison•40m ago•0 comments

Doom Running Inside Emacs

https://github.com/minad/doom-on-emacs/tree/3830991bd3d69a9426498ee4a3dc8b55c8eb2eb5
1•signa11•46m ago•0 comments

Work on the Fairphone 6 is turning it into the most modern pmOS smartphone

https://catcrafts.net/posts
3•pizzaiolo•1h ago•0 comments

Show HN: Proxy-or-Not, Proxy Detector

https://arcades.click/proxy-or-not
1•jwally•1h ago•0 comments

Adobe, RapidRAW, and the End of Selling Software as a Product

https://danunparsed.com/p/rapidraw-adobe
4•sambellll•1h ago•4 comments

Suggest some uncensored AI for photo genaration?

4•tafijul•1h ago•1 comments

A Lost Civilization Is Baffling Experts and Rewriting China's Origin Story

https://www.wsj.com/world/china/a-lost-civilization-is-baffling-experts-and-rewriting-chinas-orig...
3•cwwc•1h ago•0 comments

Free ATS keyword checker after friends sprayed 200 resumes

https://medium.com/@grhawk/i-built-a-free-ats-keyword-checker-after-watching-friei-built-a-free-a...
1•applyboost•1h ago•0 comments

Moscow Is Speaking [video]

https://www.youtube.com/watch?v=_d1AmMt6A9s
1•consumer451•1h ago•0 comments