How does hybrid typing work?

Question

Wikipedia says "Perl 6 offers a hybrid typing system whereby the programmer may choose to use static typing, use dynamic typing, or mix the two." How does hybrid typing work? Does using static typing in Perl simply mean that I declare a type, and have to explicitly cast strings to numbers and vice versa in exchange for safety and run time speed? I've noticed there seems to be very little information on this feature.

Answer 1

As I understand it, hybrid typing simply means that type annotations are supported, but optional:

my Int $i = 0; # static typing
my $i = 0; # dynamic typing

When you use the explicit type annotations, the compiler may check things for you and maybe optimize the code better. There are similar features in other languages, too, like Objective-C:

NSString *foo = @"foo"; // explicit type signature, static typing
id foo = @"foo"; // dynamic typing

Technically speaking, this is not exactly the difference between static and dynamic typing. There are languages that have a static type system that doesn’t require the explicit type annotations. In Swift or Haskell, you can say things like let f = 0 (without a type annotation) and still get static type checking thanks to type inference. See also What to know before debating type systems.

There are also other, more interesting features regarding the difference between static and dynamic typing in Perl 6, see Jnthn’s talk.