With kotlin 1.5.21 installed on my path, in my shell when I run `kotlin` and then at the REPL prompt...

# announcements

[Erik]

With kotlin 1.5.21 installed on my path, in my shell when I run kotlin and then at the REPL prompt I type (-1).toUInt() or 1u - 2u, then the result is kotlin.UInt = -1. Is that expected? kotlin.UInt ranges from 0 to 2^32-1, but can it be rendered as negative too somehow? Or is kotlin.UInt = -1 actually equal to 2^32-1?

[Erik]

Interestingly:

>>> UInt.MAX_VALUE
res1: kotlin.UInt = -1
>>> UInt.MIN_VALUE
res2: kotlin.UInt = 0

[Erik]

Very paradoxical at first sight: the max value is less than the min value mind blown

[Erik]

It seems to be a rendering issue, where Int.MAX_VALUE is the maximum value being printed:

>>> UInt.MAX_VALUE / 2u
res4: kotlin.UInt = 2147483647
>>> UInt.MAX_VALUE / 2u + 1u
res5: kotlin.UInt = -2147483648

[ephemient]

seems to be printing the underlying Int representation

[Erik]

So it seems indeed, I found that toString just converts a UInt to a Long

[Erik]

https://github.com/JetBrains/kotlin/blob/v1.5.21/libraries/stdlib/unsigned/src/kotlin/UInt.kt#L365

[Erik]

And the internal representation of a UInt is based on an Int, which can simply hold value -1, so that is what is printed

[Erik]

Oh, wait, that doesn't print -1, but correctly prints

>>> (1u - 2u).toString()
res0: kotlin.String = 4294967295

[Erik]

So it is in the println somewhere...

[Erik]

Nope, also isn't println because that also prints the correct value

[Erik]

It's in the REPL that seems to not use toString

[Erik]

>>> UInt.MAX_VALUE.toString()
res1: kotlin.String = 4294967295
>>> UInt.MAX_VALUE
res2: kotlin.UInt = -1
>>> println(UInt.MAX_VALUE)
4294967295

[andylamax]

hahahah, you gotta love these personal findings