Polymorphic dispatch is the specific reason for polymorphism in Object-Oriented Programming. It is more generically known as "dynamic dispatch": http://en.wikipedia.org/wiki/Dynamic_dispatch
Dynamic dispatch is a special case of predicate dispatch. In particular, captainmuon pointed out that:
>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
you'd write:
int foo ( gt_zero? a, int b): return a
int foo ( int a, int b): return b
>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
you'd write: