Show HN: Regex.ai – AI-powered regular expression generator (regex.ai)

294 points by regexLL ↗ HN
Regex.ai is an AI-powered tool that generates regular expressions. It can accurately generate regular expressions that match specific patterns in text with precision. Whether you're a novice or an expert, Regex.ai's intuitive interface makes it easy to input sample text and generate complex regular expressions quickly and efficiently. Overall, Regex.ai is a game-changer that will save you time and streamline your workflow.

125 comments

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I really wonder if this sort of thing is the how AI will work.

We tell AI what we want. AI produces a hyper-specific, but barely comprehensible result. We look over the result to make sure it’s all good.

Then execute.

I just used ChatGPT to create a ton of permutations for product pricing that I'm putting on Stripe as products.

Except... it made ONE ERROR that I just spent two hours tracking down and fixing in my JSON file and now in the Stripe dash. (I coincidentally found the error using ChatGPT lol).

It's probably still faster and less error-prone than I could have done it manually. But it's still error-prone...

The Reflexion paper (https://arxiv.org/abs/2303.11366) that came out recently shows how this kind of mistake might be overcome. Asking the model to think about the answer after it's generated a first draft greatly improves accuracy. Also, prompt engineering such as copying the generated code, pasting it in a new chat and saying "There's a bug in this code, please find it" can go a long way. There is so much low hanging fruit in harnessing the power of these models that is just being ignored because some even lower hanging fruit (RLHF, system messages, context window size, plugins, etc) is being released seemingly every few days.
That’s really interesting! It’s like treating this thing like a kid and telling them to really think about the answer and show the work. Weird!
I recall reading that's partly because it doesn't have an inner monologue.

It only "knows" what it writes down and if you force it to print the intermediate step it can more accurately get to the final answer.

> Asking the model to think about

These models do not "think". This is a fundamental misunderstanding of how they work. It's not AI. It's not even language. It's just text inference.

Maybe you are asking it to think and it's like, "this is 99% likely just code analysis requested"

So it's still fair to say you can ask it to think

If you ask the model to "think" about something, and then it simulates that action and outputs what the result of that might be, does it matter if it's really thinking or not? Especially if the output is what we wanted originally?

I would suggest that a person saying "ask the model to think about" in this context in no way implies that that person is confused about the nature of the model, it is simply a convenient piece of language that helps us to achieve the desired result.

> does it matter if it's really thinking or not?

Yes, it does. Assuming GPT "thinks" is shaping public perception and that's already gone much too far.

He did not say "make the model think about..." or implied the model is thinking. He simply and _correctly_ pointed that if you _ask_ the model to think it improves the answer.

It looks you just pattern-matched on the word _think_ and replied with a pre-made opinion about how AIs can't think. Ironic...

AI generates a comprehensive set of unit tests with correct and incorrect inputs, then we run the tests to ensure that they all pass.
Cool hack! I'm having some trouble thinking of a case where I wouldn't just explain to Copilot / ChatGPT what I need. Maybe specifically in cases where I had the raw data but not the column titles?
even with the examples on the landing page, the regexes generated for the emails are not really usable. it needs way more examples to produce the right thing.

even though I doubt most production code uses the actual, correct, rfc-compliant regex to match emails (it's a monster), this does nothing to improve the situation...

It really need some zero-shot or few-shot magic from LLMs, or even heuristics to detect common patterns like emails, and just generate a sane regex, rather than stuff like [A-Za-z]{2,}@libertylabs\.ai which will obviously fail with a few more examples.
It doesn’t make any sense to use a regex to check emails beside some very basic typos. Why do you need an email? To send messages to the user. Then do that: send a validation message and see if someone gets it.
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Regexes are one of those things that are much easier to write good tests for than to write the code itself. I like this use of LLM
Great to see our service rank 2nd in Hacker News! Surprise by the sudden rise in traffic.

We will be deploying regex.ai v1.1 on the first week of April , with descriptions and 5x improved performance. Stay tuned!

> Regex.ai is an AI-powered tool that generates regular expressions.

Or, just write regular expressions?

> ... Regex.ai's intuitive interface makes it easy to input sample text and generate complex regular expressions quickly and efficiently.

See: https://www.ibm.com/topics/overfitting

Inputting the sample text:

  foo bar baz
  baz bar foo
And highlighting the first "baz" produced patterns which all had "[A-Z][a-z]*@libertylabs\\.ai" included, assumedly due to the default inclusions.

Removing those and highlighting the second "baz" resulted "<Agent B>" as the results in one case.

There is no explanation of any patterns generated. If a person is to use one of the generated patterns and Regex.ai is supposed to "save you time and streamline your workflow", no matter "[w]hether you're a novice or an expert", then some form of verification and/or explanation must exist.

Otherwise, a person must know how to formulate regular expressions in order to determine which, if any, of the presented options are applicable. And if a person knows how to formulate regular expressions, then why would they use Regex.ai?

I often find it faster to write something from scratch rather than to work with someone else’s code to fix it. In the latter case I need to understand the intent, the whys behind the choices.

Well guess what, LLM-generated code is someone else’s code: an amalgamation derived from many peoples’ code. Except those people are ‘helpfully’ “abstracted away” from you by the middleman, so you can’t know their original intents and choices. What’s worse, it’s someone else’s code that will be treated as your code—unlike working with a legacy system that everyone knows was written by some guy, in this case any bugs will be squarely on you.

This offering, and the other half-dozen like it this past week or so, is like giving a kid a flamethrower.

It's all fun and games until they burn down your house.

> ... I need to understand the intent, the whys behind the choices.

As do I.

And that is something ChatGPT-X (for any given X) cannot provide, regardless of whether or not what is produced is correct. Perhaps with some form of backward chaining[0] a ChatGPT-X someday can explain how it arrived at what was produced works.

But "the why" is the domain of people.

0 - https://en.wikipedia.org/wiki/Backward_chaining

It's weird to see a forum for hackers, with hacker in the name, and with a line about encouraging curiosity in the charter, be so hostile to someone who hacked something together.

Sign of the times perhaps.

Though I guess it's not much different from the thread trashing Dropbox however many years back.

> It's weird to see a forum for hackers, with hacker in the name, and with a line about encouraging curiosity in the charter, be so hostile to someone who hacked something together.

My comment was in direct response to an overarching concern raised by the implications of incorporating "LLM-generated code." This is relevant here due to the "Show HN" description above, which reads thusly:

  Regex.ai is an AI-powered tool that generates regular
  expressions. It can accurately generate regular expressions
  that match specific patterns in text with precision.
If you interpreted my characterization of "... like giving a kid a flamethrower" as being hostile, then I extend my apologies to the OP as I was using this phrase as a literary tool detailed subsequently. I thought the subject expansion of "the other half-dozen like it this past week or so" was sufficient.

As to "encouraging curiosity", I point you to feedback I provided to the OP in a reply peer to this one.

I’m not critical of the hack itself (unless it uses OAI’s closed commercial LLMs). Just not a fan of some implications of using it in real circumstances: it might work for a personal thing but if you use it for anything important you still need to know how regular expressions work.
>so hostile to someone who hacked something together.

It's not hostile but I'm a bit tired of all those projects that sprout around AI.

If it was an open-source project full of bugs, I would understand, and encourage and give solutions to the creator of the project, maybe even create tickets or fix bugs.

But with AI, we are flooded with tons of closed-source frontends to a closed-source backend, and those projects are more than buggy since they confidently give bad solutions. It's not like a "DIY electric car project," it's someone putting pieces of cardboard on a Tesla and pretending it makes it safer or faster.

I'm dumbfounded and I don't know how I am supposed to react to this, I would certainly not release that to anyone since it's antithetical to what I do and believe what software should be.

Good point. I wish OpenAI released more of their work as open source. I wish people building on top of them did too. That said, I usually won't begrudge a small-time developer or entrepreneur from choosing whatever licensing model they think is going to make them the most money. An army of small-time entrepreneurs who build closed source can still have democratizing effects on a market that's been captured by a few large companies. I'm more frustrated when I see big, entrenched companies finding ways to capture value from the open source ecosystem and privatize it.

My view on v1s, prototypes and PoCs regardless of their licensing is that by design they're going to be a mess and have errors, if they don't you waited too long to ship. Maybe these folks should have been a little more honest in their marketing but man if we're going to get into a list of the offenders on that front I think they are way way down on that list.

Overall in my view LLMs are the most disruptive thing to come along since the Web itself. Business model's like Google's are facing a direct challenge from this technology. Why do I want to look at Google's first page full of shitty search ads when I can use a LLM to get an answer immediately? As far as I'm concerned at this stage I would love to see a billion projects from every corner of the world built on top of this technology. Whether they're great or they're crap, the avalanche is the first real opportunity in many years to disrupt some giants.

Are you trying to say that every sort of criticism equals hostility? If I dont like your half-thought-out idea, I am hostile. If I praise it, I feel like an idiot. Not much choice remaining after all....
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You have a choice of not replying at all.
Sure, that seems to be the overall way forward. Keep quiet to avoid being attacked for speaking your mind.
If I was trying to say that, I imagine I would have just said that
> It's weird to see a forum for hackers, with hacker in the name, and with a line about encouraging curiosity in the charter, be so hostile to someone who hacked something together.

I guess people are getting tired of too many topics in one narrow space. I come to HN for variety. It does get tiring when every single day I see yet another LLM-based solution attempting to solve a problem I don't think I even have.

Overdose of a certain topic is not good for a general tech forum like this. Everything should be in moderation and all that.

This forum is also against decentralization and Web3, and often shills for large centralized corporations. The ethos of hackers was always ANTI that stuff.
So if I look at most codebases, someone would be able to explain what all the code does and why it does that way? I'm extremely sceptical of that, even if I myself wrote the code 3 weeks ago.
A person should be able to explain the code they're adding to a repo at the time they are adding it. Whether or not they can explain it at some arbitrary point in the future is a different question/issue.
You can ask it to explain why. It might not be a true representation of why those decisions were made but at least it’s a plausible explanation of why something could work like that which is better than nothing. I’m not sure why you think it can’t do that already?
or you know, you can ask it to insert helpful comments
Which you can’t rely on anyway.
It's even worse. When working with someone else's code e.g. StackOverflow there's a reputation system gating people from the platform and incentivizing them to provide correct answers. You can reasonably expect that someone else's code has at least been thought through to some extent to solve the problem at hand, and very likely tested.

With LLM-generated code, especially ChatGPT-style decoder models, none of that is true. All of the posts and comments I see about it here seem to be anecdotes "it can do all of my job for me" yet asking it to write the simplest code creates several issues on my end.

Personally I think a model geared towards code generation isn't an unsolvable task; the Spider dataset was released some time ago (text to SQL task) and the winning approach there was no fanciness on the model side, but rather to just test all the output queries to ensure it's at least valid SQL. That got a 20%+ boost in accuracy.

Your experience is no less anecdotal than the millions of people who successfully use Copilot and ChatGPT to write code on a daily basis. I am one of those and can't imagine coding without Copilot or an equivalent ever again.
Define successfully. You might verify what the LLM gives you, but lots of people who blindly copy and paste from stack exchange will do the same with chatgpt
Software exists over time. There is no “successful” unless you account for future bugs.

I do believe LLM code generators can be used with good results. I just know that for me that way is slower and more painful, because I need to switch between creative mode (when I make stuff) and debugging mode (when I need to figure out how someone else’s stuff works). I find keyboard typing speed is usually not what slows me down the most…

> the millions of people who successfully use Copilot and ChatGPT to write code on a daily basis

Where did you get that number from? Are you saying that roughly one in a thousand person on Earth, alive today, is using Copilot and ChatGPT to write code on a daily basis?

Not the parent but it's not completely impossible. According to [0], there's about 25-30 million software developers in the world. If about 7-8% of them use ChatGPT and Copilot every day, it's already (two) millions.

[0] https://www.bairesdev.com/blog/how-many-software-developers-...

I guess it's early for this to matter too much for the count, but people who are not "developers" have also used ChatGPT to write code. I've read anecdotes.
I'm (genuinely) curious what kind of code you write. I haven't tried Copilot and I haven't used ChatGPT very much, but I feel I would be pretty surprised if either of them made significant improvements to my workflow.

Copilot I could see, since I already use Intellisense, autocomplete, and snippets to great effect. I'd be annoyed if I had to work without them. But in general, knowing what I want the code to do is >90% of the work of writing new code.

I feel there are a few possibilities for why I'm confused:

1. I'm not a very good software engineer, at least in certain respects. Maybe I should have a better understanding of architecture patterns or something I might have learned in a CS degree. Maybe I am hacking everything together and maybe I am already a slow coder.

2. I'm not [being] creative enough as a prompt engineer. I typically can't think of any way that ChatGPT could help me without ingesting my entire repo and figuring out the correct patterns. It could be, however, that there are ways to get the answers I need with better questions.

3. We do completely different kinds of work, and some kinds of coding are better suited for AI assistance than others.

The opposite of 1 is also possible. You're a really good programmer and know the material better, and just don't need to ask the kinds of questions that other people are asking ChatGPT (or stack overflow, or man pages) for/are happy with your current reference materials.
Like autopilot in planes that fall back to experienced pilots, we're embarking on the most dangerous "uncanny valley" maneuver where these systems will be adopted by experienced pilots who know the limits but who will inevitably be followed by either no one or students whose conception is entirely synthetic.

At that point the plane AI better be 100% TRUSTWORTHY cause there's no safe fallback.

Thanks for your feedback! Updated ver 1.1 coming soon with more descriptions and better performance :)
If you have a choice between descriptions or performance, I humbly suggest detailed descriptions perhaps with links to tutorials and/or further reading. Who cares if the wrong thing is returned quickly if that means it lacks any context.

Also, consider how to express anchoring and/or grouping preferences in the UI or weighting based on highlight positioning. These are oft used features of regex languages.

Using your example and deselecting the email addresses I end up with these suggestions:

\b(foo|bar|baz)\b

\w(foo|bar|baz)\w

\bbaz\b

[fF][oO][oO]|[Bb][Aa][Rr]|[Bb][Aa][Zz]

It only lacks a dice button which randomly selects the "correct" answer.

There are tools that somewhat explain what each part of a regex does.
I’d you don’t understand regexes well enough to write them yourself, you should not get some ai to generate them for you. You won’t be able to verify whether they do what you want and the bugs can be subtle and destructive
I read a few weeks ago here on HN about one large SAAS grinding to a halt because of a greedy selector in one line of regex. Not sure how people find old stories, it's lost to me now. But it was an excellent example of why regex is dangerous and requires a lot of care to write. I wouldn't trust an AI to write my regex unless I saw that people were finding it to be consistently better than they were are writing what they need.
You gave it an example where inferring the semantics you were after was basically a crapshoot. It’s not going to do well under those conditions. Nor will a random human who lacks insight into what specifically you are after. Did you want all the bazzes that are at the end of lines? The bazzes that follow bars? Who knows?

Try giving it examples where the data provides context cues.

This doesn't seem to generate great regex, but it does seem to generally work(ish?) so I guess nobody would care. That said, how's this work? Are you just sending this off to one of the AI api's - what's going on with the data pasted in the box after we hit run?

Struck me as funny when we have another thread going about people pasting company data into ChatGPT and here we have a regex AI with an example that looks like it's encouraging you to trust it with helping you regex through your PII, just paste it in the box and highlight what you need lol (not saying that's the intent, just that's what less savvy users may do)

Company site does not inspire much confidence: https://libertylabs.ai/

Light on details, heavy on philosophers, trend setters, idea banks, and radicals that make me worried I'm dealing with opportunists taking swings at monetizing a bunch of .ai domains. Especially the weird cinematic banner.

> Company site does not inspire much confidence: https://libertylabs.ai/

Ah c'mon. It's a bunch of kids -- which I say with envy not malice -- giving something new a go. Let 'em at it!

The products will speak for themselves. This one, meh, not so much. But we should be encouraging not disparaging.

Prompt Engineer is such a pompous title. I think AI operator would be more accurate.
How is this AI rather than just string logic? What model was trained? Trained on what? Maybe producthunt would be a better place to post promos?
Honestly, writing a regex is way easier than reading a regex, no? So it feels like now I have the harder task of proving that the generated regex is correct.
I agree. I similar arguments ("just write examples") a lot, and I really don't get that. Finding a comprehensive set of examples for code, regexps, shell, whatever is very, very hard.
Reading regex is much easier than writing them when using visualization tools such as https://regexper.com/, https://regex101.com/, and https://jex.im/regulex/, especially for beginners. I always use them to read regex.
Using regexper changed my life. I’m not afraid of even the most complex regexes anymore.
Or you can use "verbose regex" which some languages implement like in Python (https://docs.python.org/3/library/re.html#re.X). The spaces are ignored and you can add comments on each line. I used this in the past and my coworkers were happy about it because they could understand the regex and even modify it.
> Or you can use "verbose regex"

How did I not know about this! Thank you very much. This solves my biggest gripe with regex.

> my coworkers were happy about it because they could understand the regex and even modify it.

The most important point. Computers might read code efficiently, but if people can't reason about it, that is a recipe for bugs to sneak in.

I feel this is also true of code in general.

Writing is easy; reading is hard.

That's why LLMs aren't much help to me -- they just increase my workload by giving me more code to read and review. If I write it myself, I already know what it means, so that saves time and effort.

I find this mostly pays off in debugging: Having written code usually means I know it better than code I've reviewed, which I know better than code I've never seen. Finding a weird bug in code I know well is a _lot_ easier.
I consider myself a product designer so this is absolutely not true for me. Every time I try to write a Regex I have no idea how to even start. Copilot has been really good at starting me off and then I’ll take it to a regex site and understand it
For me writing a regex is easy only if I remember the syntax, which I never do because they differ between languages and I only need them once a month or so.

For me the fastest way is to ask generator to create a valid and not necessarily correct regex, so that I can tweak it. I successfully used gpt for just that recently. It even got the capture groups right.

This feels like a really cool idea for a tool - I would 100% use something that generates matching strings to a regex expression for checking my own or understanding other people's regex.
Just so that you know, your problem is called "regular expression synthesis", there's vast literature on it and a LLM is by no means necessary.

https://arts.units.it/retrieve/handle/11368/2758954/57751/20...

https://arxiv.org/pdf/1908.03316

https://cs.stanford.edu/~minalee/pdf/gpce2016-alpharegex.pdf

and yet a decent regex generator has not existed before.
This one isn't decent
How so? Other than the UI what else can be improved?
Well, I tried extracting fields from some logs I had lying around and I can tell you why I think it's not useful: 1. I select DEBUG and INFO, but it doesn't work out that there are WARNs etc in there and extract those too.

2. Some of the regexes are just.. wrong? I selected individual fields but there's one mangled regex that gives me two fields and the text in between, I didn't ask for that and it's no use.

3. None of the regexes could extract the date I selected (of the form 2023-03-28 05:23:28.844); some of the 'agents' used the literal date, the only one that broken it down into \d's didn't match anything because the DEBUG and INFO were mangled into there.

I'm not really sure how this would be at all useful in its current form?

Well, I know nothing about AI and tried with simple variations of "foo bar baz."

The only solutions that worked were either "\w+ \w+ \w+..." which does not filter anything and may produce errors with other content, or "(first line|second line|third line)" which could be replaced by a bunch of if statements.

The other solutions were plainly wrong but at least they are honest about it and it's shown in the user interface.

For me it's more than useless and I get faster results with https://regex101.com/.

How do I tell it to generate a regex for emails? Try selecting the emails. all four generated Regexes are wrong. Even if one of them was right? how do I choose between 4 choices if I Don't know the meaning? I have to verify the generated Regexes, Veryfing complicated regexes is much harder than writing them in first place.
My Google search results for "regex generator" returned a full page of decent ones.
Finally I can use this to write a regex to parse HTML! (Glad to finally able to bust out the meme)
Coming soon: an AI powered regex explainer.
The most basic check - that the suggestions are working - is missing
That would make it look broken when it's part of what it is. Why should it pretend to be something else? It's not an algorithm that produces a specific result.

Edit: I got a message saying there were too many requests. So much for not appearing broken. And I'm not using a VPN or anything so I'd appear as ordinary traffic.

Writing regexps by hand, indeed, might be tedious task in some cases.

One I familiar with is to match datetime interval, when you need to narrow down log rows for a particular time range.

So I built a tool just for it :) https://github.com/ekiauhce/interval-to-regexp

How is this compare to GPT-4? I am using it to write regex all the time nowadays.
To be honest I find ChatGPT sufficient for regex. I usually ask it for test cases that I can then validate in a regex playground to make the regex is working as expected.
Exactly my thought. I can just go to GPT and ask it for regex related stuff. Why do I need a dedicated AI for that? I don't.
This might make people put more unnecessary regexes into code, because AI. Beware.
Just as with every AI tool you need to be an expert in scope that you are operating the AI tool...

You have to know reg-ex really well to use this tool safely.

Very useful tool for novices, though I'd assume experts will much rather write one themselves...

P.S. assuming the poster is scanning the comments, typo in the site title: "aritifical"

imo using chatgpt for generating regex is better, good project although