Welcome to the Opa page! Here, you'll find a description of the language as well as a list of sample programs in that language.
In version 0.9.0, it natively supported MongoDB, as if it had an ORM built in. In 1.1.0, this support was extended to PostgreSQL too.
It reminds me a bit of React/JSX, as it's wholeheartedly designed for interoperability with HTML. It's actually a first-class citizen. Blurring the line between client and server code is something that I'm really fond of.
The problem is that, having had only 2 years of activity, the "user experience" is really bad. Setting up the environment is... problematic, to say the least. It requires installing NodeJS and OCaml, with dependencies of each one sprinkled in. Which in turn need dependencies. Some of which have to be compiled from source. In a time where installing a language (or anything really) should not take more than 2 or 3 commands (apt update && apt install -y Stuff-0.1.1-dev), this was a paaaain.
Luckily, there's this cute technology called containers.