When will there be a conditional construction in the assignment as in Java?

Language Design
1

In Java
bool boolean = true;
String s = boolean ? “true” : “false”;
I want the same in Kotlin

2 
val boolean = true
val s = if(boolean) "true" else "false"

See also:

2 Likes
3

Yes it is, but it didn’t stop Java.) I’m killing a lot of time writing simple instructions.

4

I doubt it will be ever added, as it duplicates the existing and recommended syntax.

1 Like
5

I agree with you, this Kotlin syntax is cumbersome. Kotlin syntax is generally nicer than Java, except for this conditional syntax, which is a shame.

6

There’s already been a centi thread on this:

I see little reason for this to change at any time

7

You can’t compare this directly with Java. Java’s if…else… construct is a statement, not an expression, and so it needs a special syntax for a conditional expression (just like C before it).

However, Kotlin’s if…else… is an expression. You don’t need anything else — it’s already right there in the language! Why clutter up the language with multiple bits of syntax doing exactly the same thing??

(And is writing ‘if’ instead of ‘?’, and ‘:’ instead of ‘else’, really so onerous? If the extra 4 characters is ‘killing a lot of time’, then maybe you could get some typing lessons or something? :​-)

5 Likes
8

Well, type faster, my fingers are not rubber. You can also write “;” and “begin … end” for beauty. I don’t mind if Kotlin replaces mine ?: on if else. Although it’s strange not to keep up with Swift.

9

I wonder if you could combine infix functions?

infix fun <T> Boolean.`?`(options: Pair<T, T>): T = if (this) options.first else options.second

infix fun <T> T.`:`(other: T): Pair<T, T> = this to other

boolean `?` "true" `:` "false"

(I’m using the backticks because I’m pretty sure you’d have to escape the question mark and colon characters)

Now that I write it out, I can see another reason for not adding ternary expressions… since the question mark is already used for all sorts of null checks, and the question mark + colon is used for the Elvis operator, it might make the compiler very complicated if it also has to interpret question marks and colons as a ternary expression.

10

This works, but it doesn’t really replicate the functionality of if, because it always evaluates both sides. For lazy bahavior, you would need something like

infix fun <T> Boolean.`?`(options: Pair<() -> T, ()  -> T>): T = 
    if (this) options.first() else options.second()

But then you would have to write

boolean `?` {"true"} `:` {"false"}
1 Like