Why doesn't UInt have a toDouble()?

Question

Consider:

val foo: Int = 1 foo.toDouble() // ok  val bar = 2.toUInt() bar.toDouble() // error! 

This doesn't make sense to me. Why wouldn't UInt have toDouble? (it also doesn't have .toFloat).

The docs say:

Every number type supports the following conversions:

• toByte(): Byte
• toShort(): Short
• toInt(): Int
• toLong(): Long
• toFloat(): Float
• toDouble(): Double
• toChar(): Char

So it should be possible. The error I get is:

Error:(11, 4) Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: @InlineOnly public inline fun String.toDouble(): Double defined in kotlin.text 

Is UInt not considered a number type? Or is it something else?

Answer 1

This appears to be coming in 1.3.30, according to this YouTrack request.

1.3.30 was just recently tagged and appears to be releasing very shortly.

Answer 2

Is UInt not considered a number type?

Yes, it doesn't extend Number class.

Declaration of Int:

class Int : Number, Comparable<Int> 

Declaration of UInt:

inline class UInt : Comparable<UInt> 

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Starting with Kotlin version 1.3.30 UInt has toFloat and toDouble methods.