But I am already thinking about what the code should do. The problem is that if I read functional code I get bogged down in the details of what limits are set b

But I am already thinking about what the code should do. The problem is that if I read functional code I get bogged down in the details of what limits are set by the operations, because they're usually not as explicit. It's like reading a chain of functions on some element (actually, it quite literally is that).