Option<T>

Safe handling of nullable values

Replace null/undefined checks with a type-safe container that forces explicit handling

What is Option<T>?

Option is a container that either holds a value (Some) or represents the absence of a value (None). It eliminates null pointer exceptions by making nullable values explicit in the type system.

// Create options
const value = Option("hello") // Some("hello")
const empty = Option(null) // None

// Transform values
const upper = value.map((s) => s.toUpperCase()) // Some("HELLO")
const _nothing = empty.map((s) => s.toUpperCase()) // None

// Chain operations
const result = value
  .map((s) => s.length)
  .filter((len) => len > 3)
  .getOrElse(0) // 5

// Pattern matching
const message = value.fold(
  () => "No value",
  (s) => `Value: ${s}`,
) // "Value: hello"

Key Features

Type Safety

TypeScript enforces explicit handling of empty cases, preventing runtime null errors

Chainable Operations

map, flatMap, filter - transform values without null checks

Pattern Matching

Explicit Some/None handling with fold() and match()

Composable

Works seamlessly with Do-notation for complex workflows

Common Patterns

Creating Options

Option(42) // Some(42)
Option(null) // None
Option(undefined) // None
Option.none() // Explicitly create None

Transforming Values

const doubled = Option(5)
  .map((x) => x * 2) // Some(10)
  .filter((x) => x > 5) // Some(10)
  .getOrElse(0) // 10

Pattern Matching

const option = Option("test")
option.match({
  Some: (value) => `Found: ${value}`,
  None: () => "Not found",
})

When to Use Option

✓

Function return values that might not exist

Database queries, array searches, user input parsing

✓

Optional configuration or parameters

Default values, optional fields in objects

✓

Chaining operations where any step might fail

Validation pipelines, data transformations