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

Third Interconnect Attack to Break AMD SEV-SNP

https://xca-attacks.github.io/staleus/
1•pipogipo•41s ago•0 comments

FPGA-Accelerated Lock Management and Transaction Processing

https://arxiv.org/abs/2605.13398
1•teleforce•1m ago•0 comments

From physical therapy, dance to workout with real-time coaching

https://apps.apple.com/us/app/workout-dance-for-all/id6765586514
2•donchurchill•3m ago•1 comments

The Field Guide to CSS Grid Lanes

https://gridlanes.webkit.org/
2•ingve•8m ago•0 comments

Junior Devs Who Use AI Are Not Cheating – They're Training Smarter

https://theaileverageweekly.com/posts/junior-devs-who-use-ai-are-not-cheating-they-re-training-sm...
1•talvardi7•8m ago•0 comments

Stolen Lego, Mormons and corrupt Cops – a recap of all the major facts

https://illumdig.substack.com/p/stolen-lego-mormons-and-corrupt-cops
1•dan_ryan•11m ago•1 comments

Study links joint pain supplement to accelerating dementia

https://ufhealth.org/news/2026/study-links-joint-pain-supplement-to-accelerating-dementia-2
2•supermatou•11m ago•0 comments

Show HN: HolaClaw, an OpenClaw Distro for macOS

https://holaclaw.ai/
1•ridruejo•11m ago•1 comments

What if gravity broke for 60 seconds?

https://www.youtube.com/watch?v=dNWwIfjJXZY
1•Asheed•13m ago•0 comments

India exploring $1 tax per 100GB

https://telecom.economictimes.indiatimes.com/news/industry/mobile-data-tax-could-burden-low-incom...
1•amtamt•16m ago•1 comments

Why Artificial Intelligence Is Not a Subject

https://slavoj.substack.com/p/why-artificial-intelligence-is-not
1•miniBill•19m ago•0 comments

Surface Duo

https://news.microsoft.com/surfaceduo/
3•tosh•21m ago•0 comments

The future of Siri, or: why private inference isn't private enough

https://blog.cryptographyengineering.com/2026/06/09/apples-siri-ai-or-more-shouting-into-the-void...
2•supermatou•21m ago•0 comments

Murder: Ruby Script to Kill Processes

https://codeberg.org/EvanHahn/dotfiles/src/commit/843b9ee13d949d346a4a73ccee2a99351aed285b/home/b...
1•thunderbong•24m ago•0 comments

Tars: Tiny automatic recycling system, a prototype desktop injection moulding ma

https://manutechlab.com/tars
3•fanf2•27m ago•0 comments

Show HN: 4DGS Recording

https://splatcam.com/
1•captainbenises•31m ago•0 comments

Xcode 27 ships with agent skills, and you can export them

https://petegoldsmith.com/2026/06/10/2026-06-10-xcode-27-agent-skills/
1•theraven•32m ago•0 comments

Apple Updates App Store Guidelines with Stricter Rules for Low-Quality Apps

https://www.macrumors.com/2026/06/09/app-store-guidelines-low-quality-apps/
3•tosh•32m ago•0 comments

Goodbye, Leaf-and-Spine Networks?

https://blog.ipspace.net/2026/06/goodbye-leaf-spine-networks/
1•ram_rattle•35m ago•1 comments

Building Real-Time Risk Monitoring for 24/7 Crypto Markets

https://medium.com/@DolphinDB_Inc/crypto-never-sleeps-neither-should-your-risk-management-6f740a7...
2•CrazyTomato•37m ago•0 comments

Show HN: OpenClaw and Hermes Agent call each other via XMPP

https://github.com/ai-sns/openclaw-hermes-agent-network
3•photonberne001•39m ago•0 comments

WebAssembly 3.0

https://webassembly.github.io/spec/core/
3•tosh•41m ago•0 comments

European sentiments towards the US hit an all-time low

https://ecfr.eu/publication/home-alone-europeans-are-ready-to-defend-themselves/
4•marcyb5st•42m ago•0 comments

Show HN: WebCLI – what if the browser was just another Unix command?

https://webcli.sh
1•keepamovin•43m ago•0 comments

AWS Bedrock to require sharing data with Anthropic for Mythos and future models

12•TomAnthony•48m ago•2 comments

SpaceX IPO demand is approaching four times oversubscribed

https://www.reuters.com/world/spacex-ipo-demand-is-approaching-four-times-oversubscribed-source-s...
2•JumpCrisscross•51m ago•0 comments

The German town where people print their own money [video]

https://www.youtube.com/watch?v=WzijH3lgzHI
1•Cider9986•51m ago•0 comments

Build an Atmospheric Website

https://atproto.com/blog/atmospheric-website
1•ZacnyLos•51m ago•0 comments

Linux developers are using AI vibe coding to keep vintage AMD GPUs alive

https://www.tomshardware.com/software/linux/linux-developers-are-using-ai-vibe-coding-to-keep-vin...
3•01-_-•52m ago•1 comments

Bluesky was launched as a Twitter rival – but it's less popular

https://www.cnbc.com/2026/06/04/bluesky-twitter-rival-reddit-social-media.html
1•01-_-•53m ago•2 comments