Scope Functions
KOTLIN › Language Idioms
Drills let, run, with, apply, and also: receiver, return value, and idiomatic use.
Scope functions are a staple Kotlin interview topic because picking the right one signals idiomatic fluency, not just syntax. Interviewers test whether you know each function's two distinguishing axes: what it returns (lambda result vs the context object) and how it references the object (this vs it). Expect to justify choices like ?.let for null-checks, apply for configuration, and also for side effects.
What this covers
- What each of let, run, with, apply, also returns: lambda result vs the context object
- Which functions expose the object as this (run, with, apply) vs as it (let, also)
- Idiomatic null-safety with ?.let and why it beats manual null checks
- apply for builder-style configuration and returning the configured object
- also for side effects (logging, validation) without breaking a call chain
- Choosing run/with for grouping calls and computing a result, plus non-extension run
Study this topic
- Scope Functions explained: the guided lesson
- 14 practice quiz questions
- 9 revision flashcards
- Scope Functions interview questions and answers