Edgar Rodríguez

🛠️I've been creating various Domain-Specific Languages (DSLs) since the start of my career over 14 years ago. I've built maybe a dozen of various external DSLs and embedded DSLs. 🚀Every time this was the best decision that impacted the architecture of my applications in a good way. On the pictures: 1⃣ External DSL for Spaceship Control Software (quite rich in PL features) 2⃣ Type-level eDSL for the game objects and properties in Haskell 3⃣ eDSL for interaction fiction games like Zork: Grand Inquisitor 🙄DSLs are underrated in the industry. 😞Partially because we have scarce resources on how to build your own. 🫤Partially because Domain-Driven Design ignores Domain-Specific Languages completely. Instead, it talks about Ubiquitous Language which has a broader meaning than DSLs. However, with no code representation, UL is just a blah-blah that is yet to be designed and developed. 😖Partially because DSLs are mistakenly mythologized to be a part of Programming Language Design. "You should be as smart as Computer Scientists or should be the one to develop a DSL!" 🚫🔬🚫 Nope. Taking DSLs as a scientific task similar to building a regular programming language is unnecessary at least and wrong at most. ⛔️Forget about those extinct animals called bison, yacc, and lex. These ones are for a Serious PL Business™️. If you're wondering if you need it, you don't. Otherwise, you knew enough to not even ask this question. ➡️ Simple external interpretable DSLs can be made over XML, JSON, or even YAML. In this case, you don't even need to write parsers manually. ➡️ ADT-like interpretable external DSLs are also easy to build with Haskell's Read and Aeson features. ➡️ Monadic parsers such as Haskell's parsec and megaparsec can handle more complicated external DSLs with ease. 💠Embedded DSLs are another joy in programming to practice. I'd even argue it's more fun than bending your mind around smart things, type-level stuff, and metaprogramming. 📑In particular, eDSLs allow to encoding of the domain in the purest way so they are well-suitable for collaboration between developers and non-developers. 😃😃I did it several times, and I've seen this process in the wild. It worked extremely well. This allowed us to 🚢 the functionality much faster and to be clear about what we're actually doing. 💪DSLs have the power to enhance software quality, improve the understanding of the domain, and reduce the complexity of its encoding. 🎇Also, building DSLs is a lot of fun. I can't leave this post without recommending some literature. 📘Building User-Friendly DSLs, Meinte Boersma 📗Domain Specific Languages, Martin Fowler, Rebecca Parsons 📙Domain Specific Languages, Andrzej Wąsowski , Thorsten Berger 📚I'm a big fan of DSLs, and I believe our software could be much better written if it had more DSLs embedded into it.