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Ask HN: Are Domain Specific Languages Still a Thing?

• shatteredvisage 8y ago
  I last developed a small DSL in 2016 at my last company that's still in production. I haven't seen another since!
  • quickthrower2 8y ago
    “That’s still in production” says nothing. Rarely is any code taken out of production once it’s put there in my humble experience. Not to rain on you though: good work getting a dsl out there.
• walterbell 8y ago
  Do code generators count, e.g. https://chisel.eecs.berkeley.edu https://chisel.eecs.berkeley.edu
• JohnFen 8y ago
  I'd count the likes of AWK, shell scripting, PostScript, Perl, and even (depending on how you define "language") HTML as domain-specific languages, so they do seem to be a thing still. Personally, I tend to use them quite a lot in my own projects. These aren't commercial (and often aren't released at all), so might not count. Still, it's very handy to be able to embed a DSL into a complex project to provide programmability, and most of the modern scripting languages tend to be too large and/or too slow for my purposes. My DSL of choice for this tends to be TCL-based, as I can easily extend the language in task-specific ways and drop the parts of the language that aren't useful for the task at hand. This results in something capable, tiny and fast.
• btilly 8y ago
  The hype comes and goes, but they always have and always will be, in one form or another. But they don't always get called DSLs. Put the idea in your toolbox, and use where appropriate. Call it a DSL or something else based on what is currently cool. Good programmers have long known that you should build your language up towards your application, and then write your language within that language. What tools are available to do that and where the line is drawn will vary. But you'll find customized languages buried in your database (SQL), configuration languages like https://github.com/vstakhov/libucl https://github.com/vstakhov/libucl, specialized build configuration languages like make or ant, regular expressions for text matching, and so on. Some languages encourage building external languages that you then parse and act on. Others encourage customizing an existing language to your needs. (Our Glorious Leader published a book in the mid-90s on doing that with Lisp, see http://www.paulgraham.com/onlisptext.html http://www.paulgraham.com/onlisptext.html for details.) There have even been languages which are designed to be easily implemented in other languages, with whatever customizations you want. For example I personally worked with code from the 1980s that implemented a Forth variant to write financial models in. But the idea doesn't have to be literally a new language. Squint sideways at any API, object model, or library and you can see it as a language. Conceptually there is a close parallel between scripting web services, and writing a TCL script that uses prebuilt commands written in C. If you can see the parallels and see how principles from the one apply to the other, the odds are that you'll be doing both better. Whereas if you don't see it and reinvent the wheel from scratch, you're going to wind up learning lessons the hard way that were learned many, many years ago. All that said, writing and maintaining a language is significantly harder than writing business code. Therefore you'll always see rather more people writing code in languages, than writing languages to make code easy to write.
  • marktangotango 8y ago
    Good, very concise All that said, writing and maintaining a language is significantly harder than writing business code. The same can be said for writing good APIs and libraries, isomorphic to your second point.
• segmondy 8y ago
  Every complex program is a DSL interwoven with the programming language, so yes. Unfortunately most languages are terrible at separating the DSL from the main language like most lisps.
• thedday 8y ago
  What about something like Robot Framework? It is used as a test language and is in widespread use to test websites as well as embedded systems. The underlying language is Python, a scripting language which might also be a DSL under some definitions.
• kasey_junk 8y ago
  DSLs are endemic in the ops stack. Think HCL for terraform or VCL for varnish.
  • cbluth 8y ago
    nginx, cloudformation, and any other JSON-y extension out there
• ken 8y ago
  By "DSL", do you mean only a text file bundled with the application? I'd say the simple answer is that the median language got a lot more powerful. We write DSLs in code now, just like Lisp programmers have all along. We just don't tend to call them a "DSL" any more.
• bjourne 8y ago
  People in the thread have been citing HTML and SQL as examples of DSLs. Those are examples of universal languages but not of domain-specific languages as envisaged by the proponents of DSLs. The DSL "philosophy" as presented in for example The Pragmatic Programmer from 2000 was that every programmer should write his or her own domain language as the situation requires. That every project should come equipped with its own language, codifying that business problems business rules. That philosophy, and the surrounding hype, has completely died down. Put simply, it wasn't a good idea. More languages makes it harder to communicate, not easier. Plus, writing a good DSL that someone other than the creator of said DSL can understand is tons of work. Instead, what one aims for is generality.
  • usgroup 8y ago
    ggplot2 is a solid dsl example. Use it with margrittr. I agree with this in the main unfortunately ... I was a proponent of DSLs and did my best to try make them whenever practical. The only pattern that’s worked out for me is the builder pattern. This doesn’t require much work, and you get something functional that works as you might expect that people appreciate. Again ggplot, epic example. Other examples , Varnish, Dockerfile, Nginx, ufw, etc
• m0llusk 8y ago
  JavaScript is universal domain which kind of shorted out the metaphor. CSS is web front end. R is big noodles. Perl is good for parsing HTML with regular expressions.