I've tasted sum types and if I was trying to be snarky I'd say so have millions of Java enterprise developers who fill their code with a healthy dose of instanc

I've tasted sum types and if I was trying to be snarky I'd say so have millions of Java enterprise developers who fill their code with a healthy dose of instanceof and null :) It is somewhat anathema to the OO idea and brings lots of (runtime) implementation concerns so I can understand the delay.