A case for inline type annotations

[smueller]

@lud

def hostname(%URI{host: host} :: URI.t() | String.t() | nil) :: String.t() | nil, do: host
def hostname(url :: URI.t() | String.t() | nil) when is_binary(url) :: String.t() | nil, do: hostname(URI.parse(url))
def hostname(nil :: URI.t() | String.t() | nil) :: String.t() | nil, do: nil

Using Rust, Typescript, Kotlin, and Swift for inspiration, this could be:

def hostname(%URI{host: host} :: URI | String?) :: String?, do: host
def hostname(url :: URI | String?) when is_binary(url) :: String?, do: hostname(URI.parse(url))
def hostname(nil :: URI | String?) :: String?, do: nil

And now there’s no question of readability, which furthers my point: modern languages have already solved this elegantly and concisely.