To me, the major difference is that the Java solution gives you one solution. The Go solutions gives you the building blocks. The latter has the advantage you

To me, the major difference is that the Java solution gives you one solution. The Go solutions gives you the building blocks. The latter has the advantage you get to recompose the system in new ways, yielding greater flexibility. In Java, a better compositional framework is probably Erik Meijer's et.al's RxJava. Haskell also provides better compositionality due to it's functional structure and lazy evaluation semantics.