That is not an especially big production problem. Of course you don't want it to happen. But it rarely happens. And it happens even less if you use -XStrictData

That is not an especially big production problem. Of course you don't want it to happen. But it rarely happens. And it happens even less if you use -XStrictData or manually make your record fields strict since that's by far the most common cause: lazy records used as accumulators. I would say in my 5 years of production Haskell, I've seen that sort of thing deployed in production _maybe_ once, and I've run into it during development once or twice. One time it was in integration testing, and a simple heap profile made it clear it was in a library dependency. And a quick look at the library source was enough to diagnose it. It was like an hour or two tops from "we have a space leak somewhere" to "here's a PR to a third-party library fixing the leak."