Though they share the word "algebraic", algebraic data types != algebraic effects. And while Java has good support for concurrency primitives and concurrent data structures, it does suffer from the problem highlighted in the article:
> Over time, the runtime system itself tends to become a complex, monolithic piece of software, with extensive use of locks, condition variables, timers, thread pools, and other arcana.
I'm not an expert on this, but my understanding is that the problem that algebraic effects tries to solve is to improve language semantics to make it easier to separate different levels of abstraction (e.g. separating the what from the how), while also encoding the performed effects into the type system.
> Over time, the runtime system itself tends to become a complex, monolithic piece of software, with extensive use of locks, condition variables, timers, thread pools, and other arcana.
I'm not an expert on this, but my understanding is that the problem that algebraic effects tries to solve is to improve language semantics to make it easier to separate different levels of abstraction (e.g. separating the what from the how), while also encoding the performed effects into the type system.