Haskell Pro

This is a solid choice if you're working in Haskell and want help with the advanced stuff: GADTs, type families, STM concurrency, effect systems, that sort of thing. It pushes you toward pure functions, total over partial, and newtypes for domain modeling. You'll get idiomatic code with strong type signatures, property-based tests, and sensible project structure advice for Cabal or Stack. The approach is pragmatic rather than academic, which means it won't drown you in category theory unless the problem actually calls for it. Good for production Haskell where you want maintainability and type safety without overthinking every abstraction.