Not the OP but let's take a tree. In F# it's trivial to describe what a tree structure is with the type system. In Java, you'll need to use the Composite pattern and write classes (tree + leaf) to create a tree like structure. Thus the Composite pattern is made irrelevant in F# since an algebraic type system allows you to describe an intent without writing imperative code.
Good type systems are a trade-off between complexity and expressiveness, but it's something that is hard to get right. Obviously Java's type system is simpler thus in theory easier to learn. But in practice F#'s is easier to use if understood and might lead to smaller thus more maintainable code bases.
https://en.wikipedia.org/wiki/Composite_pattern
https://en.wikipedia.org/wiki/Algebraic_data_type
Good type systems are a trade-off between complexity and expressiveness, but it's something that is hard to get right. Obviously Java's type system is simpler thus in theory easier to learn. But in practice F#'s is easier to use if understood and might lead to smaller thus more maintainable code bases.