That example is for positional args with default values, according to the example usage: `greet("Alice")`. Can't find ruby-style keyword args example, with or without default values. maybe no kw args in t-ruby?
Yeah, it doesn't work with keyword arguments. In the playground I tried a simple keyword with default value, and it converted to the wrong thing, as if "someone" was a valid type.
def greet(name: "someone"): String
"Hello, #{name}!"
end