Function type inheritance in Scala

[Saanvi S]

Hi Scala folk,

"Function types are classes that can be inherited from subclasses."

I know that I can create new classes, and I know that functions are
objects and hence have a type.

I don't yet know how/if scale distinguishes between a type and a
class, but for now I'm not assuming that there is a distinction.

A function type might be something like "(Int,Int)String" (possibly
I'm confused on this point, perhaps its type is Function or something
like that).

The statement conjures up an image of me declaring a function type the
way I would declare a class:
class (X,Y)Z

and then subclassing that function type somehow (not sure what there
would be to inherit, since the entire implementation of the function
would be overridden).

Thanks in Advance

Saanvi S

[Vlad Patryshev]

Actually, the types of functions are Function1...Function26 (as far as I remember). If you subtype a function, you subtype one of these.

Thanks,
-Vlad

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[Alexey Romanov]

In Scala, you can write the type e.g. `(Int, Int) => String`, but it's just a short way to write `Function2[Int, Int, String]` (it's actually a trait, not a class). And yes, you can write

class Foo extends (Int, Int) => String {

  override def apply(x1: Int, x2: Int): String = ...
}

Yours, Alexey Romanov