`BooleanArray(64) { (long shr it) and 1 != 0 }`

# announcements

[karelpeeters]

BooleanArray(64) { (long shr it) and 1 != 0 }

[LastExceed]

i see, and how would i convert back?

[karelpeeters]

Hmm that's not quite as convenient, probably just a for loop is best.

[karelpeeters]

You can also consider using a BitSet from Java, it can convert back and forth to a long array.

[karelpeeters]

It's not actually that bad: arr.foldIndexed(0L) { i, a, b -> a + if (b) 1 shr i else 0 }

[LastExceed]

now you've lost me

[karelpeeters]

Take a look at the source code of fold, it applies the lambda repeatedly to the previous result and the next element of the array. It's a common functional idiom, I'm sure there's lots of information about this online.

[LastExceed]

ok ty

[karelpeeters]

And in this case it basically ends up being sumByLong which is missing from the stdlib I think.

[LastExceed]

hmm your code to convert back to Long always returns 1 but I can't find the bug

[karelpeeters]

It has to be shl.

[LastExceed]

ty

[Dico]

You can also make your own class wrapping the long value with functions to set bits, if you're specifically looking for 64 values.

[LastExceed]

could i make an inline class that uses [] syntax to access the individual bits? and yes i am specifically looking at Long values

[LastExceed]

thanks!