My experience is exactly the opposite. Using the type system is less effort, guides your development more and, in a way, provides more consistent guarantees than spending time on a wide unit test coverage.
Obviously, these things are not totally mutually exclusive though.
What are the two static & dynamic languages you’re comparing by the way?
In other languages with a less sophisticated type systems I would need to build validation functions manually and obviously test them. Hell, an interpreted language might even boot up with functions that have faulty code, ultimately producing runtime errors when invoked. Haskell generally would not (because of the type system). Adding type constraints basically limits the range of possible inputs/outputs, requiring you to write far less tests.