It's one of the things I really like about scala, x call y is always equivalent to x.call(y)

This combined with relaxed method name restrictions allow you to do "operator overloading" in quite a sane way and allow you to write bigint + 1 or set contains element.

Kotlin is a bit more conservative and only translated the built-in operators to fixed methods: + to the plus method etc.

The worst part is there is a talk by Steele called Growing a Language about designing Java where specifically talks about the importance of overloading so that things like future number representations like BigInteger can be first class

Do you have examples of real world code you had to write with BigInteger? just for amusements sake

Write your program on ints and then transform it with sed before compiling.