Is there any reason why this works: (implementing...

# language-proposals

[Emil Kantis]

Is there any reason why this works: (implementing a functional interface by delegation)

object ColorEncoder : Encoder<Color> by { Encoder { appendable, t -> appendable.appendColor(t) }}()

But inlining the lambda body to this doesnt:

object ColorEncoder : Encoder<Color> by Encoder { appendable, t -> appendable.appendColor(t) }

(I get that we can use a val instead, but would like to use objects to keep things consistent)

[Kroppeb]

What if you put it in parentheses?

[Emil Kantis]

Parentheses work.. 👍

[Emil Kantis]

But it would be nice if they weren't required 🙂

[Emil Kantis]

But then it's simply a matter of how the code is parsed

[Ben Woodworth]

Yeah it's probably just because it's lexically ambiguous. Same with extending an abstract class whose last primary constructor arg is a lambda. The lambda needs to be within the parentheses

[Ben Woodworth]

Kotest and Spek come to mind, with test classes like this

class MySpec : Spec({
  // tests
})