Add LocalDispatch example demonstrating arrow operator

[codegod100]

This PR adds a new example demonstrating the -> arrow operator for local dispatch.

Overview

The arrow operator -> replaces the pizza operator |> from old Roc. It passes the left-hand value as the first argument to a function in local scope.

What's Demonstrated

• Basic local dispatch: 5->double
• Chaining: 3->double->add_ten->square
• Mixing method syntax (.method()) with local dispatch (->func)
• Comparison with traditional nested function calls

Example

# These are equivalent:
double(5)
5->double

# Chain reads left-to-right instead of inside-out:
7->double->add_ten->square
# vs: square(add_ten(double(7)))

Note

This example uses new Roc syntax and will work once the examples repo is updated to new Roc.

[Anton-4]

Thanks @codegod100, this looks great :)
I'm just going to set this to request changes to make sure we do this before merging:

• Move this to a single file notebook format that can execute code and run "invisible" tests. Support for this is not yet implemented in the current Roc CLI.