Unit is the worst naming

[Raman.Gupta]

@hax

BTW, someone in the discussion said Swift do not have “Nothing”. It’s wrong, Swift also have it, just name it “Never”.

Not exactly. The Never type is not a subtype of all types, therefore it is not the same thing as Kotlin’s Nothing type.

For example, as far as I know in Swift you cannot implement Kotlin’s TODO function – this program results in error: cannot convert value of type ‘Never’ to specified type ‘String’:

func TODO() -> Never {
    fatalError("This is not implemented yet")
}

let f: String = TODO()

That being said, there is a Swift proposal open to change this which specifically references Kotlin’s Nothing type in a positive way.

@hax

And, TypeScript also have “void” and “never” types, with the same names like Swift. I think both TypeScript and Swift have the right names, compare to kotlin.

The names reflect the purpose in the language – in Kotlin its the bottom of the type system, and in Swift its used for functions that never return. Nothing is a noun and Never is an adverb, and types are usually nouns. Swift is also considering making Never a bottom type – if they do that, their naming will sound weird/wrong unless they introduce a new type.

Yep, naming is hard, but IMO Kotlin made the right decision here.

@hax

I don’t know why kotlin use “Unit” in the first place, especially Java already have “Void” (the Box type for void). Technically it’s just unit type (the only valid value is “null”), and it also can be used as generic param. IMO, it’s nothing wrong and it’s better to reuse java “Void”.

We’re just circling back to prior discussion now.