Pattern: Use of double negative lambda
Issue: -
Detects negation in lambda blocks where the function name is also in the negative (like takeUnless).
A double negative is harder to read than a positive. In particular, if there are multiple conditions with && etc. inside the lambda, then the reader may need to unpack these using DeMorgan's laws. Consider rewriting the lambda to use a positive version of the function (like takeIf).
Example of incorrect code:
fun Int.evenOrNull() = takeUnless { it % 2 != 0 }Example of correct code:
fun Int.evenOrNull() = takeIf { it % 2 == 0 }