Hacker News Reader

Comment by dunk010 | Hacker News Reader

If you re-read my reply, you'll see that I said that regex is a DSL, but doesn't apply for different reasons.

I did read your reply, and I think your reasons for excluding it are insufficient. You can't just exclude any DSL that succeeds (has become "universal") and say "see? no DSLs are good!" The point of me noting how people resisted (and still resist) regular expression usage is to note that just like any other DSL there are those that dislike it and eschew its use and instead just write the code. It is exactly what the article is talking about, where it advocates writing in the base language and not using a DSL.

If you're going to make a serious argument that "DSLs are, universally, awful" then you're going to need to account for regular expressions a bit more carefully. That can be you admitting that you just dislike them and don't use them so consider them awful as well, but if you don't hate them then you may want to focus on the why, and it is likely a much more interesting conversation topic to pursue than "DSLs bad".

Regular expressions ... this representation is a somewhat fundamental and mathematically general representation of interacting with strings - the DLSs in question here are, quite obviously, nothing of the sort.

https://en.wikipedia.org/wiki/Regular_language

Regular expressions have a deep mathematical background. An ad-hoc DSL from a company that specifies infrustructure does not.

Regular expressions, as used in practice in programming are mathematically general for interacting with strings, but they are in no way fundamental. They are a DSL for generating NFAs and DFAs (depending on the underlying engine). There is nothing fundamental about them, they are just a shorthand (a DSL) for those abstractions. Indeed, the very article you posted notes that anything able to be implemented as a finite automaton is also a regular language due to Kleene's theorem.

> Regular expressions have a deep mathematical background. An ad-hoc DSL from a company that specifies infrustructure does not.

You very specifically went far beyond making any statement about ad-hoc DSLs from companies that make infrastructure. You said "DSLs are, universally, awful".

I'm also interested why you left out makefiles in your original rebuttal. I think makefiles are a good example a simple and useful DSL for accomplishing what it sets out to do. That's not to say it can't turn into a mess (what language, domain specific or not, is free from that concern?), not that it solves all needs to all people, but makefiles are simple, straightforward, solve a useful problem, are well known by many people (and easy to explain and teach), and I don't think most people would consider them a mathematical concept core to computer science. Are they awful? If so, why?

You're grasping at straws now. Just admit that regex is a much more fundamental technology than some ad-hoc, badly specified commercialware and we can be done. Go on, you can find it in yourself ;-D.

Sure, Makefiles are a DSL. Just a horrible one. They just make my point in a different way. Have you used a Makefile recently? They are AWFUL. Brittle, complex, half-bash, invisible-tab-prefixed, abominations, sent from another millenium. Let's take a modern codebase - say Python - you're much better to just use something like pyinvoke - handles all the CLI-level stuff, and you get the full force of the programming language you were writing in the first place.

You seem to have fundamentally misunderstood my purpose for engaging you. I tried repeatedly to move the conversation from a poorly supported absolutist statement from you to a productive discussion about what makes a DSL good or bad, but you're only interested in defending yourself and your over encompassing statement, not in actually having a discussion. Such as why does being fundamental in some way make it a good DSL? Are all fundamental concepts worthy of a DSL?

In any case it's clear you're uninterested in engaging on that and nor are you willing to consider your statement carefully and actually support it with additional examples (beyond some puzzling critiques of makefiles which make me think you don't understand the point of a DSL at all) or walk it back to a reasoned examination. So I'm not sure we'll get much out of continuing this.

I think you’re giving yourself quite a bit too much credit there. Most of this discussion you’ve been trying to argue about regex. We can drop it up to a higher level, sure, but you seem to only want to do that to avoid conceding in the specifics.

As I’ve quite clearly said, regex is a good DSL - so I obviously do think, and have argued above, that there is a split between “good” and “bad” DSLs, but examples of good ones are vanishingly scarce.

I think, given that it’s your position that DSLs are generally good; or at least that there are many examples that you find fine, then it’s upon you to provide examples. So far you named Makefiles, which are hilariously bad, but your response to my comments on it was basically some lazy ad-hominem, so I don’t hold out hope for any actual intelligent analysis.

But as I have outlined above there is a giant chasm of difference between mathematically-backed deep and broad DSLs, and… some ad-hoc commercialware that iterates towards being a full language but with bad, ad-hoc design and worse tooling.

The real issue here is a DSL without intention of enforcing limitations permanently.

A Regex, SQL, TLA, CSS and so on are all better DSLs than allowing a general purpose language because they are meant to restrict inputs of lower priority than other goals, where priorities are largely fixed.

A corporate DSL is meant to expand to whatever grandiose plans the company has for accepting impractical input from platinum customers.

Reply on news.ycombinator.com