(Heavy IHP and Django user here)
Just yesterday we shipped a bug into prod that our tests haven’t cought. It took a while to trigger but resulted in wrong data in the DB which was a PITA to correct manually. That was with Python. I’ve checked, and that particular error wouldn’t have happened with Haskell.
Can’t wait till IHP gets a simple admin area similar to Django’s, I’d use it for new internal products in a heartbeat. (For now we “only” use it for important user facing parts, where its safety and JSX-like templates are key)