From brain driven developmentIt turns out, that every Function youll ever define in Scala, will  become an instance of an Implementation which will feature a certain  Function Trait.There is a whole bunch of that Function Traits, ranging from Function1 up to  Function22. Since Functions are Objects in Scala and Scala is a statically typed  language, it has to provide an appropriate type for every Function  which comes with a different number of arguments. If you define a  Function with two arguments, the compiler picks Function2 as the  underlying type. Also, from Michael Froh's blogYou need to make FunctionN classes for each number of parameters that  you want? Yes, but you define the classes once and then you use them  forever, or ideally they're already defined in a library (e.g.  Functional Java defines classes F, F2, ..., F8, and the Scala standard  library defines classes Function1, ..., Function22)So we have a list of function traits (Scala), and a list of interfaces (Functional-java) to enable us to have first class funtions.I am trying to understand exactly why this is the case. I know, in Java for example, when I write a method say, public int add(int a, int b){    return a + b;}That I cannot go ahead and write add(3,4,5);( error would be something like : method add cannot be applied to give types )We simply have to define an interface/trait for functions with different parameters, because of static typing?
The idea of functionN in Scala / Functionaljava
scala;functions