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Kotlin Academy · Lesson

Option and Nullable: When to Use Each

Compare Arrow's Option type with Kotlin nullable types and choose appropriately.

Two Ways to Represent Absence

Kotlin has built-in nullable types (T?) that represent "a value or nothing." Arrow also provides Option — a sealed type with Some(value: A) and None. Both solve the same problem but fit different contexts.

Kotlin Nullable Types

Kotlin's T? is the idiomatic choice for absence in most Kotlin code. The compiler enforces null checks, the safe-call operator ?. chains calls gracefully, and ?: "default" provides fallbacks concisely:

val name: String? = findUser(id)?.name
val display = name ?: "Anonymous"

All lessons in this course

  1. Either : Typed Error Handling Without Exceptions
  2. Arrow Raise DSL: Composing Typed Errors
  3. Option and Nullable: When to Use Each
  4. Functional Domain Modeling with Arrow's Core Types
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