<Reddit question>, but curious if anyone knows - why does function declaration use ":" to designate ...

# random

[Ryan Rolnicki]

Reddit question, but curious if anyone knows - why does function declaration use ":" to designate the return type, but lambda syntax uses "->"? Was there some language design reason this was required?

[ephemient]

honestly the -> really bugs me in swift and python (typing); : is consistently property/function return type in Kotlin

[ephemient]

so it is inconsistent with function types, but if they used : then we'd have declarations like

val callback: (): Unit

and I think that's worse than -> just for that case

[Ryan Rolnicki]

It is but - why not -> for everything then?

[ephemient]

because in every other use case, it's : Type

[ephemient]

class Child(...) -> Parent

is definitely questionable, and function syntax and class declaration (especially with primary constructor) syntax mirror each other

[Ryan Rolnicki]

A Child doesn't return a Parent; hence, the distinction

[andylamax]

I think I am with you @Ryan Rolnicki,
: should still remain for inheritance and type specification for properties and function arguments
-> be used as a return type

Although to be fair, the current syntax is not confusing at all. It is easy to pick it up with very little effort

[Jason5lee]

: Type
-> code