[bojo]

My software team uses Haskell to help build tooling and support around an enterprise ISP environment. It's a shift in thinking from standard imperative/OOP programming, however, what we've gained is confidence in maintaining and refactoring systems that constantly change due to business reasons over the period of years.

Purity helps quite a bit with narrowing down bugs; you simply check that your inputs and outputs are correct without having to ever worry about state. We use effects to narrow the types of functions that can be legally called inside specific domain logic, which also narrows down a large class of bugs that we've seen creep into other code bases.

However, it's not a magic bullet. Time to getting someone unfamiliar with Haskell up to speed can be costly. Discovering time-saving idioms in a sea of bad documentation is frustrating. Smaller ecosystem than other popular languages means less blogs, and in Haskell's particular case the information seems either too low or high level with no in between.

Still, with 250k of production lines running as stable as can be, we have no complaints.