Interesting ``` class Foo: (key: String) -> Str...

# announcements

[kirillrakhman]

Interesting

class Foo: (key: String) -> String

gives an error "Unsupported: named parameter in function type in supertype position", but

typealias KeyFunction = (key: String) -> String
class Foo: KeyFunction

actually works.

The benefit is that when you let IDEA generate the missing members, the parameter name is set to key instead p1

[elect]

I don't get, you can make a class extending a lambda? Purpouse?

[kirillrakhman]

you can make a class extend a function type. usecases are debateable, but it's definitely possible

[elect]

can you name one?

[kirillrakhman]

When you have a function that should accept a provider of some value. in some cases, the implementation is so simple that you'd want to implement it using a lambda so you use typealias Provider = (Foo) -> Bar. But in other cases, the implementation is more complex and has dependencies, so you implement it using a standalone type class MyProvider: Provider