Troubleshooting¶

Structurally Equal Objects Are Both Present¶

That is the point of this library. Identity collections use ===, not equals.

data class Id(val value: Int)

check(identitySetOf(Id(1), Id(1)).size == 2)

If you want structural uniqueness, use Kotlin's standard mutableSetOf, distinct, or distinctBy.

A Mutated Object Is Still Found¶

Identity collections are insensitive to changes in an object's structural hash code. Lookup is based on the reference, so mutating properties that participate in equals or hashCode does not move the entry.

Null Keys And Values¶

Ref(null) is supported and identity collections can store null when their Kotlin type allows it. All null references are the same null identity.

check(identitySetOf(null, null).size == 1)