Redundant 'asSequence' call

Reports redundant asSequence() call that can never have a positive performance effect.

asSequence() speeds up collection processing that includes multiple operations because it performs operations lazily and doesn't create intermediate collections.

However, if a terminal operation (such as toList()) is used right after asSequence(), this doesn't give you any positive performance effect.

Example:

  fun test(list: List<String>) {
      list.asSequence().last()
  }

After the quick-fix is applied:

  fun test(list: List<String>) {
      list.last()
  }

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

RedundantAsSequence

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Kotlin | Style issues

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection RedundantAsSequence

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025