What is a domain specific language? Anybody using it? And in what way?

A domain specific language is a language that's written to deal with a specific domain or set of concerns. There are a lot of them around, like make, ant, and rake for describing software builds, or lexx and yacc for language construction. In recent years, they've become popular as some things have combined to make them easier to build. Big among those things has been the increasing popularity of Ruby, which has several features that make it easy to build new DSLs.

Martin Fowler is a big proponent of the idea, as here.

You can think of DSLs as complex arguments for functions written in a more general programming language. The real programming language parses the DSL code and does something with it, typically, the DSL code only focuses on the what you want to do, and the larger system figures out the how.

Examples of DSL include all query languages (SQL, XPath, ...), all template languages (Django, Smarty, ...), shell scripts, especially including stuff like twill, a command driven web browser (mostly used for automated test), data storage and exchange languages (XML, YAML, ...), and document languages like LaTex, HTML or CSS.

Some languages with very flexible syntax like TCL and Lisp build their DSL directly into the language... when possible. The majority of languages use strings, usually loaded from external files.

Are there any particular advantages of using them? Using them for their intended purposes is very advantageous to the point you will turn to them without knowing, just like you have been using (I presume) SQL or HTML without thinking of them as DSLs.

I'll dare saying there are enough DSLs out there for any sort of application you may need; you almost certainly don't need to learn how to write your own one.

(addressing the crux of the question)

I think the first time I saw DSL somewhere and its definition as "domain specific language" I also thought it was a particular, concrete language that I just hadn't heard about -- but, no, its a general term for languages that are tailored to a particular application area.

Ironically, if you had just heard about TCL as a "tool command language" you might think, like DSLs, that there would be lots of TCLs for various tools -- but, no, its the specific name of a particular scripting language.

I think it's a language suited to solve problems for a specific domain. It could be some rule-processing language or service description language.

An opposite to a domain specific language (DSL) is a general-purpose language.

A DSL is a good way to develop a language to be used by non-programmers. For example, if you have a DSL for the finance people in a company, then rather than programming to their specification you can just let them write the program they want done. Then, if it is too slow then you can take what they wrote that works as they want, write it in a compiled language to speed it up.

Well! there is lot of things explained above. I will try to explain this in much simpler way as some one like me come will understand.

As general purpose languages are used for vast purposes the DSL is only made for specific domain. Like HTML or CSS.

You can say if you wrote instructions to a paper which only some person or your only best friend can understand and no one else could. Then it may be a DSL. But if you wrote instruction in such terms which many people could understand and could follow then this is not DSL.

I onces created a Switch board for user which could be operated via Serial port of a computer and User want a program for that board which could be executed on that board and Relay switches will be turned on and off accordingly. So I wrote some instructions and told the user to program that board according to these instructions. This is an example of DSL. I did not invented a new Language rather then I just created bunch of Strings that micro controller could read from EEPROM and could parse accordingly and could perform a specific task.

An example of a DSL used in Machine Learning is patsy in python: https://patsy.readthedocs.io/en/latest/formulas.html#

which is based off the formula DSL from R: https://stat.ethz.ch/R-manual/R-devel/library/stats/html/formula.html

https://cran.r-project.org/web/packages/Formula/vignettes/Formula.pdf

and Hadley has a nice section of his advanced R book that describes how to build a DSL w/R: http://adv-r.had.co.nz/dsl.html

Once the deep learning field stabilizes somewhat (or even now) I'd love to see something similar arise inside Apache MXnet project. However, I haven't seen any proposal for that on the proposal page yet though.

Domain-specific languages express your domain processes and knowledge in a language that directly uses the concepts and logic from your particular field.

The community is definitely growing but still not in the level of other "mainstream" technologies.

Most of the time, DSLs are made to improve productivity inside the companies, so they keep it private and don't share their results/insights.

Here is a conference where the speaker gives some examples of DSL using JetBrains MPS, with the technology of Projectional editing: https://vimeo.com/197381453

DSL - domain specific language. Let's start what is domain - domain is some defined area, scope. This domain can be web site look, and you have for it CSS and second domain can be web site structure, and here you have HTML.

But, domain can be also Company X Application. And in scope of this domain some language can be created. Language does not mean - fully flavored thing with own gramma, syntax, compilator or runtime. DSL can be just a list of tools which solve domain problems.

Lets consider OOP and its model to represent domain objects by classes and methods as those objects behaviors. If we create such structure, and give these objects behaviors, then we can write a code using those concepts. Consider this pseudo code example:

cookie = async getCookie(cookieId)
user = async getUser(userId)
result async user.buy(cookie)
if (result.isError()) {
  error.showAlert("User has not enough money")
} else {
  confirmation.showSuccess("Cookie was bought")
}

How much from above is GPL (general purpose language) and how much is specific domain terminology and tools. This is a mix of two, but all commands are here domain specific. That said we can say that above is written in DSL where the domain is some application x.

Going forward with this example I can create even more abstract tools, and mostly perform the control flow by those tools, consider (this is more FP, but hope you get what I mean):

waitForMany(getCookie(cookieId), getUser(userId)
  .andThen([cookie, user] -> user.buy(cookie))
  .andThen(showSuccess("Cookie was bought"))
  .whenError(showError("User has not enough money"))

As you can see I was able to abstract quite a lot and use this abstraction to perform the control flow. And everything is based on GPL and works in scope of GPL.

To reveal the truth, we all write DSL, every domain specific abstraction which u can use is kind that. But most of those abstraction are not complete solutions, that is why we tent not to use this word too often. But if you have set of tools, functions which abstract your domain, they form kinda DSL.

What is also DSL, many things, for example any framework which provides set of rules is DSL. If you see somebody is claiming he is React developer, then you know he is Domain Specific Developer, as React is exactly DSL which is alternative for using native web platform. If you can compose functionality from existing domain specific tools then you are writing using DSL. Going deeper in React, sorry all folks not from this DSL :D, you can create set of components, and compose them as building blocks, and hurra!, now you made DSL on top of DSL.

Yep repeated DSL too many times here, sorry.

nextflow(https://github.com/nextflow-io/nextflow ) is a kind of DSL language written by groovy;

the main purpose of nextflow is to write pipeline for analysis, and easily trans from laptop to HPC to cloud, and repeat env with conda,docker,singularity