| ▲ | Show HN: Rust but Lisp(github.com) |
| 97 points by thatxliner 6 hours ago | 53 comments |
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| ▲ | ecto 4 hours ago | parent | next [-] |
| Readers may enjoy my lisp, Loon, which takes heavy inspiration from Rust https://loonlang.com/guide/ownership |
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| ▲ | imachine1980_ an hour ago | parent | next [-] | | How does ownership work within the Lisp tree structure?, What is the difference between ownership on this setting and ARC? | | |
| ▲ | ecto 40 minutes ago | parent [-] | | ARC refcounts everything (many owners) whereas Loon refcounts only inside immutable shared tree nodes (one owner per handle) |
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| ▲ | akch an hour ago | parent | prev | next [-] | | That page is beautiful! What ssg / theme are you using to build it? | | | |
| ▲ | kibwen 2 hours ago | parent | prev | next [-] | | Agreed, a Lisp built around the concept of ownership is much more interesting than just a way to write Rust via S-expressions. | |
| ▲ | thatxliner 28 minutes ago | parent | prev [-] | | Honestly, that's very cool That was basically my intent with this project, but I took the laziest way to get there lol |
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| ▲ | hawkice 5 hours ago | parent | prev | next [-] |
| I think some comments are missing the upside of it being precisely Rust, without any new semantics. If you want lisp that compiles to machine code, Common Lisp can get reasonably efficient. The purpose of bringing Rust into it is to surface Rust-specific semantics -- which many people quite like! |
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| ▲ | vermilingua 5 hours ago | parent | prev | next [-] |
| Claims to have all the syntax covered, but not a single example of specifying lifetimes or the turbofish, some of the trickiest rust syntax |
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| ▲ | thatxliner an hour ago | parent | next [-] | | You can also drop into direct Rust with the (rust "...") macro if I forgot to implement anything | |
| ▲ | kibwen 4 hours ago | parent | prev | next [-] | | If you already have the ability to express the grammar productions in Rust that allow for optionally-specified types (e.g. variable declaration), then you have the ability to express lifetimes and the turbofish (which is just a curious way to call a generic function with a specific type parameter). The only weird thing would be that Lisp uses the apostrophe character for something very different than Rust, but you could just pick any other way to denote lifetimes. | | | |
| ▲ | kccqzy 3 hours ago | parent | prev | next [-] | | The HRTB is probably the trickiest syntax for specifying lifetimes. It looks like `for<'a> F: Fn(&'a (u8, u16)) -> &'a u8`. | | |
| ▲ | stdatomic 3 hours ago | parent [-] | | Can you translate this for those of us who don't speak rust? | | |
| ▲ | Xirdus 2 hours ago | parent [-] | | Type F must be a function that's generic over any possible lifetime 'a, with a single argument that's a reference with lifetime 'a to a tuple of two numbers, and returns a reference with the same lifetime 'a to an 8-bit number. The full code is usually something like: fn foo<F>(callback: F) where for<'a> F: ... Which is a generic function foo that takes the argument of type F, where F must be... |
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| ▲ | andrepd 4 hours ago | parent | prev [-] | | It's a vibecoded parser... | | |
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| ▲ | skulk 2 hours ago | parent | prev | next [-] |
| So if I wanted to actually use this and I write some rust-but-lisp code and there's a compile error, will it show me a nice error message with an arrow pointing to where the error happened in my lisp code? Can I use the amazing `rust-analyzer` LSP to get cool IDE features? I suspect the answer is no, but these might be good further prompts to use. |
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| ▲ | GalaxyNova 5 hours ago | parent | prev | next [-] |
| It seems like this is more like writing Rust in an s-expression syntax instead of having a proper lisp dialect that compiles to Rust, which is cool I guess but not very interesting. It's quite weird-looking for someone who's done any amount of lisp programming. |
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| ▲ | noosphr 5 hours ago | parent | next [-] | | >Rust semantics with LISP syntax. A transparent s-expression frontend that compiles directly to Rust — no runtime, no GC The first paragraph says literally that. | |
| ▲ | monocasa 4 hours ago | parent | prev | next [-] | | Yeah, it sort of reminds me of the microcode assembly of a few of the lisp machines, that, while in s-expressions were also clearly not lisp themselves. But could be an interesting target for some lisp macros. | |
| ▲ | shawn_w 5 hours ago | parent | prev [-] | | A let that defines variables that have a lifetime beyond the scope of the expression? Yeah, that's really unusual. And it's not even the oddest looking thing from the first example block of code. |
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| ▲ | jaggederest 4 hours ago | parent | prev | next [-] |
| Unfortunately, given the clear LLM basis of this project, s-expressions aren't a great choice. I've found coding agents struggle really hard with s-expression parentheses matching. Much better to give them something more M-expr styled, I think a grammar that is LL(1) is probably helpful in that regard. Basically the more you can piggyback on the training data depth for algol-style and pythonic languages the better. |
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| ▲ | thatxliner 29 minutes ago | parent | next [-] | | If anyone is curious, I've been making this using DeepSeek v4 Flash with Claude Code as the harness | |
| ▲ | gleenn 3 hours ago | parent | prev | next [-] | | That has definitely not been my experience as of late. I have produced multiple, largeish Clojure projects with AI that have been perfectly formatted and functional. Perhaps you were using an older or possibly smaller model? I am admittedly using Claude with higher end models and mid to high effort but it has been working great for months for me at this point. | | |
| ▲ | jaggederest an hour ago | parent [-] | | Nope, but to be fair when you're working on your own novel S-exprs you don't have LSPs to guide the coding agent. I imagine that it works a lot better in the context of a known and understood language environment like Clojure, CL, scheme, etc. The other option would be to write an LSP in a non-S-expr language to ensure that no turn can end with mismatched parens, for example. |
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| ▲ | dleslie 3 hours ago | parent | prev | next [-] | | Opus 4.6 handles elisp just fine. But I suppose YMMV. | |
| ▲ | 2ndorderthought 3 hours ago | parent | prev [-] | | Why are we even spending time on this. It's vibe coded slop. The creator probably never even ran it before it got to HN |
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| ▲ | stevefan1999 2 hours ago | parent | prev | next [-] |
| Greenspun's tenth rule of programming is an aphorism in computer programming and especially programming language circles that states:[1][2] Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp. Maybe we should one day include Golang or Rust to it https://en.wikipedia.org/wiki/Greenspun%27s_tenth_rule |
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| ▲ | kibwen 2 hours ago | parent [-] | | Greenspun's tenth rule was formulated in a time before things like first-class functions were commonplace in industrial languages. Rust supports not just functional programming idioms but outright Scheme-style macros, it's out of scope for Greenspun's. |
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| ▲ | NooneAtAll3 an hour ago | parent | prev | next [-] |
| does there exist something that can do the opposite? some pre-processor that "compiles into rust" from less awful syntax? |
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| ▲ | chrisweekly an hour ago | parent | prev | next [-] |
| Should be named "Rutht" |
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| ▲ | OhMeadhbh 4 hours ago | parent | prev | next [-] |
| How do you change the syntax to eliminate reverse compatibility? I guess you could change the names of most key functions between releases. But to be compatible with rust you would need to make breaking changes every release. |
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| ▲ | stuaxo 5 hours ago | parent | prev | next [-] |
| "no runtime, no GC, just" I am BEGGING every project to not have this LLMism in their docs. It reads as No X no Y just slop to me every time. |
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| ▲ | andrepd 4 hours ago | parent [-] | | It's completely nonsensical too. Why would a parser for an alternative syntax introduce a GC?! |
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| ▲ | amelius 4 hours ago | parent | prev | next [-] |
| This is probably what Rust's internal ASTs look like. But why would you want to input programs as ASTs? |
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| ▲ | physPop 4 hours ago | parent [-] | | so you can do the transformations (see the rlisp macro section) | | |
| ▲ | amelius 4 hours ago | parent [-] | | Yes, but you could do the same by transforming Rust's ASTs. The only downside is that your input format is different from the format you are transforming. But the upside is that readability is much improved, which matters because code is typically read far more often than it is written. |
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| ▲ | thatxliner an hour ago | parent | prev | next [-] |
| For everyone who is shaming on the project for "not implementing enough," then you can definitely help me with it. For everyone who is shaming on the project for being "LLM slop," sure but that's the reason why something like this can exist in the first place. The point isn't to be a finished, production-ready product. The point is to be an interesting work, and just a sly bit silly |
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| ▲ | nxobject 4 hours ago | parent | prev | next [-] |
| "Lust", or "Risp"? |
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| ▲ | zephen 2 hours ago | parent [-] | | Nah. It's sort of, but not quite, like "El jefe" "L rut piss" |
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| ▲ | eiiot 2 hours ago | parent | prev | next [-] |
| > compiles directly to Rust — no runtime, no GC, just (s-expr → .rs → binary). Can we please write our own READMEs before posting to HN? |
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| ▲ | moron4hire 3 hours ago | parent | prev | next [-] |
| I don't understand why this had to be LLM generated. S-expression syntax parsers are not hard to write. That's rather much the point of S-expressions. |
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| ▲ | Maxatar 3 hours ago | parent [-] | | >S-expression syntax parsers are not hard to write. I'm not sure I quite understand the point of your comment. Are you implying that LLMs should be used for very hard to write code? I feel like the best use of LLMs is to automate the easy stuff so that I can focus on the hard to write stuff. |
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| ▲ | slopinthebag 3 hours ago | parent | prev | next [-] |
| How is pure unbridled AI slop like this making the front page? Voting rings? I don't even feel bad saying this because clearly OP is just the front for Claude here. |
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| ▲ | FrankWilhoit 6 hours ago | parent | prev [-] |
| And for why? |
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| ▲ | macmac 6 hours ago | parent [-] | | To get proper macros. | | |
| ▲ | fao_ 5 hours ago | parent [-] | | Scheme already has hygenic macros, I don't get why you'd vibecode a worse (less battle tested, llm-generated) replacement. I'm not sure why this hit the front-page, to be honest, because it doesn't seem noteworthy or interesting (Anyone and their mother can vibecode something like this in eight hours) | | |
| ▲ | wk_end 5 hours ago | parent | next [-] | | Scheme doesn't have Rust semantics, though? | |
| ▲ | zem 5 hours ago | parent | prev [-] | | this is not a replacement for scheme, it's simply an alternative syntax for rust |
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