That's because Java, like C#, makes it really painful to define a new type. When it takes huge amounts of boilerplate to define a new type to hold a piece of du

That's because Java, like C#, makes it really painful to define a new type. When it takes huge amounts of boilerplate to define a new type to hold a piece of dumb data, of course nobody does it! In F# it's one line of code, so it's idiomatic to define dozens of tiny types and use them to constrain the semantics of your program.