This is not a language flamewar, Haxe really do looks great and one should use the language he feels the more comfortable with. But I wanted to show how Ruby Duck Typing can handle this kind of situations.

typeParams.rb

# Ruby is using Duck Typing, rather than checking types, Ruby checks if an object can or cannot respond to a method.
# Here is a "port" of the Haxe example in Ruby.
# Ruby is not a compiled language, so that the "easiest" syntax comes with some shortcoming, 
# those errors can only be detected at runtime, your favorite IDE won't warn you before :)

ints = [1, 2, 3]
strings = ["a", "bb", "ccc"]

def biggerThan1(x)
  x > 1
end

def longerThan1(x)
  x.length > 1
end

def array_delete_if(array, method)
  array.delete_if{|i| send(method, i)}
end

array_delete_if(ints, :biggerThan1) # [ 1 ]
array_delete_if(strings, :longerThan1) # [ "a" ]

array_delete_if(strings, :biggerThan1) # Comparison of String with 1 failed (ArgumentError)
array_delete_if(ints, :longerThan1) # undefined method `length' for 1:Fixnum

I took actually ruby as an example:
array.delete_if{|item| item>1}