swift initializes nullable variables automatically...

# language-proposals

[elect]

swift initializes nullable variables automatically to null, could kotlin do the same?

[karelpeeters]

It's nice to have an error when you forget to initialize something in the else branch, this comes up with if a lot:

val x: Int?
if (bool) {
    x = 5
}
print(x) //error

[karelpeeters]

Automatic initialization would remove that error completely.

[louiscad]

Don't be too lazy, risking lack of explicitness

[elect]

given it's nullable, you think about it, being null is actually legit

[elect]

@louiscad laziness is a risky objection, people could say the same over other things we already have, such as type inference

[louiscad]

Karel showed how useful it is to make a difference with deferred initialization and null initialized. The compiler uses that to check correctness of the code.

[elect]

actually that is an invalid example.
If you declare it as nullable, it means null is a valid state

[elect]

if you want to catch those errors, declare it as non-nullable

[karelpeeters]

I know, it's intentional. null is a valid state but I want to explicitly set the variable in each branch to make sure I don't mess up.

[elect]

then I think it's a very rare situation

[karelpeeters]

Really? What is your use case where you don't want te be this explicit?

[elect]

I mean, you want a nullable and you want anyway the compiler to throw an error whenever you forget to set a value other than null. It looks pretty niche to me

[elect]

if you think about, declaring non-nullable type serves exactly that purpouse

[karelpeeters]

I did a grep in my current code, turns out I have no instances of either case (null-initialize a variable to later overwrite it or non-initialize it and then set it in both branches). Still, I like the consistent rule that you need to initialize everything.

[louiscad]

This is helpful at writing time.

[elect]

@karelpeeters then use non nullable together with lateinit

[karelpeeters]

But then it isn't a val anymore. lateinit is just a typesystem hack, not really a solution.