You wouldn't use a sledge hammer to hang a picture, would you?
Java is a great language. It's been running swaths of the internet for decades. It's stood the test of time, even if it's acquired some baggage over those 25/30 years. It's fast, it's incredibly secure, it's featureful, and the tooling is in my opinion the best of any language out there. Spring is largely a joy to write full stack applications with. There's just one problem, the build tooling. Maven and Gradle are needleslly complex for those who don't need a 20 foot wide toolbox filled to the brim with Snap On. Most of the time, when I'm working with Java, it's in Spring and the microservices are deployed largely the same way. An embedded Tomcat server with the Spring Web Starter. Espresso aims to fill the void of simple build tooling.
Espresso is relatively opinionated. We have one good way (at least we think) of how everything should be done. And that's not changing. If you want a custom feature, fork it! It's MIT licensed!
Every project that uses Espresso ships with the executable of Espresso it was designed to use. There's no runtimes or wrappers to manage, it's compiled code designed for your system.
Developers LOVE to over-engineer solutions from the beginning, building things from the beginning to support hundreds of thousands of users that 99% of applications will never come close to achieving. Why should the build system reflect that? I should be able to init a new project, add some endpoints, build an uber JAR and ship it. Not worry about acquiring 5 different plugins for Spring, Shade/Shadow, Compiler Plugins, etc. If you build with Espresso, and your application DOES grow to need a build system with more features (congrats!), switching to Maven or Gradle is possible. You'll probably need to refactor away some tech debt anyways.
Groovy is cool, I guess..? I hate it as a configuration language though. No one ever has a straight answer for how to configure plugins. Espresso uses YAML because it's ubiquitous and readable.
We're not going to be motivated financially to push our users to use our commercial products. We want to see the Java ecosystem grow and succeed, hopefully becoming on par with languages like Go and Rust (Love you, Cargo).
Inspired by Nixpkgs and Flatpak, The Espresso Registry is maintained as a public GitHub repository to maintain
accountability within the community. We want to grow trust. Espresso registries are simple .zip files that
mimick the structure of the existing registry, and anyone can start one!
As opposed to having community developed plugins, our "extensions" will be merged in with main and toggled on or off per project with a configuration value. With this, you get full editor IntelliSense thanks to JSON Schema. While some might claim this increases the filesize of the Espresso executable, it's a tradeoff of efficiency versus developer quality of life.