Eh, in practice I haven’t missed explicit (closed) sum times as much as I thought I would. I started using Haskell many years ago (20-ish?) and have written some medium-size apps with it, and I’m very comfortable with using "switch x := y.(type)" in Go where I would use an ordinary "case y of" in Haskell. The only thing missing here is a compile-time check for completeness.

Missing polymorphism is a valid complaint but it hasn’t had the impact I thought it would.

Meanwhile, some of the programs I had written in Haskell I’ve rewritten in Go, e.g. due to problems with the use of finalizers (causing crashes!) in Haskell. You can chalk this up to poor library design but it simply isn’t a problem in Golang, which seems to avoid the finalizers more than other languages.

I’m going to continue using both Go and Haskell, I’m happy with both.

Emulating sums with interfaces isn't the worst but proper sums with exhaustive checking make it way easier for the consumers of your code to also perform matches in a maintainable way. When I emulate sums, I keep the matching internal and at best I expose a function that is the equivalent of an exhaustive match (which takes a function per case)

I've never run into finalizer issues (or finalizers at all really) in Haskell but I'm sure they exist. What libraries in particular used finalizers that you had issues with? In general though I find resource management much easier in Haskell thanks to bracket, ResourceT, and the (imo very good!) exception handling stuff. Async exceptions in particular are a surprisingly nice feature when combined with threading!

The biggest place lack of parametric polymorphism hurts is in concurrency. I have to hand-roll so much concurrency in Go and I don't really have a good option for abstracting over various patterns.

> I'm going to continue using both Go and Haskell, I'm happy with both.

Yeah same here. I'm glad to have them both in my toolkit.

I'm not asking for specifics but do you use Haskell at work? Is it in academia? I have worked for several large and small corps and no one has used Haskell. Most use C++, a lot use Go, a few use some rust, but none of them were using Haskell. I met people who use Haskell in their spare time because of their love for CS things, but never in production code.

Without specifics..I've been writing Haskell professionally & in production for several years now for multiple companies.

None were academia & most were commercial enterprises (that most people have heard of)