Is Fortran a multiple dispatch programming language?

Interface blocks (introduced by the interface keyword) are often used for generic interfaces. They work like C++ generics, no dynamic dispatch. You must distinguish static dispatch and dynamic dispatch. Both Fortran and C++ only have single dynamic dispatch by polymorphism using classes and inheritance/overloading.

But interface blocks themselves have several independent kinds of usage in Fortran and only some deal with some kind of overloading. Often they just work like a function declaration in a C++ header.

Take the example from https://www.geeksforgeeks.org/function-overloading-c/ :

void add(int a, int b)
{
  cout << "sum = " << (a + b);
}
 
void add(double a, double b)
{
    cout << endl << "sum = " << (a + b);
}

In Fortran you can do the same but instead declaring both subroutines with the same name straight away, you define two specific subroutines with a different name and make a generic interface for them

interface add
  procedure add_ints
  procedure add_doubles
end interface

...

subroutine add_ints(a, b)
  integer :: a, b
  print *, "sum = ", (a + b)
end subroutine
 
subroutine add_doubles(a, b)
  double precision :: a, b
  print *, "sum = ", (a + b)
end subroutine

This is the good old static dispatch.