>Pattern matching in functional languages solves this in a different way.

captainmuon wanted a more flexible way of dispatching on types similar to what can be done with Pattern matching (which is also a special case of predicate dispatch).

In the post I linked to above this example is given:

Basically, instead of basing the dispatch on an "is_a" check, you check whether a general predicate is valid on the argument. So, in imaginary syntax instead of writing

  int foo( int a, int b):
  if a > 0 
	return a
  else
	return b-a

  int foo ( gt_zero? a, int b): return a
  int foo ( int a, int b): return b