Option

Functions for working with Option<T> (Some(v) / None) values.

Functions

Function	Signature	Description
Option.map	(Option<T>, (T) -> U) -> Option<U>	Transform the inner value if present
Option.flatMap	(Option<T>, (T) -> Option<U>) -> Option<U>	Chain option-returning operations
Option.unwrapOr	(Option<T>, T) -> T	Extract value or use default
Option.isSome	(Option<T>) -> boolean	Check if value is present
Option.isNone	(Option<T>) -> boolean	Check if value is absent
Option.toResult	(Option<T>, E) -> Result<T, E>	Convert to Result with error for None
Option.filter	(Option<T>, (T) -> boolean) -> Option<T>	Keep Some if predicate passes, else None
Option.or	(Option<T>, Option<T>) -> Option<T>	Return first Some, else second
Option.orElse	(Option<T>, () -> Option<T>) -> Option<T>	Lazy fallback chain
Option.values	(Array<Option<T>>) -> Array<T>	Extract all Some values, discard None
Option.mapOr	(Option<T>, U, (T) -> U) -> U	Map + default in one step
Option.flatten	(Option<Option<T>>) -> Option<T>	Unwrap nested Options
Option.zip	(Option<T>, Option<U>) -> Option<(T, U)>	Combine two Options into a tuple
Option.inspect	(Option<T>, (T) -> ()) -> Option<T>	Side-effect without changing the value
Option.toErr	(Option<E>) -> Result<(), E>	Convert to Err if present (for { data, error } patterns)
Option.all	(Array<Option<T>>) -> Option<Array<T>>	Collect all Some values, None if any missing
Option.any	(Array<Option<T>>) -> Option<T>	Return first Some, or None
Option.guard	(Option<T>, U, (T) -> U) -> U	Bail with fallback on None, continue with unwrapped value (for use)

Examples

// Transform without unwrapping
let upper = user.nickname
  |> Option.map((n) -> String.toUpperCase(n))
// Some("RYAN") or None

// Chain lookups
let avatar = user.nickname
  |> Option.flatMap((n) -> findAvatar(n))

// Extract with fallback
let display = user.nickname
  |> Option.unwrapOr(user.name)

// Lazy fallback chain
let config = localConfig
  |> Option.orElse(() -> envConfig)
  |> Option.orElse(() -> defaultConfig)

// Convert to Result for error handling
let name = user.nickname
  |> Option.toResult("User has no nickname")

// Filter — keep Some only if predicate passes
let longName = user.nickname
  |> Option.filter((n) -> String.length(n) > 3)

// Zip — combine two Options
let pair = Option.zip(firstName, lastName)
// Some(("Alice", "Smith")) or None

// Handle { data, error } pattern (TanStack Query, Supabase, etc.)
let { data, error } = supabase.rpc("get_entries", { query }) |> Promise.await
error |> Option.toErr?              // bail if error exists
let rows = data |> Option.unwrapOr([])

// Collect all Options
let allNames = [Some("Alice"), Some("Bob"), None]
  |> Option.all   // None (one is missing)

// Optional JSX rendering — render if present, nothing if absent
<div>
  {user.nickname |> Option.map((nick) -> <Badge>{nick}</Badge>)}
</div>
// None renders nothing (undefined is ignored by React)

Guard Pattern

Option.guard combines with use for early returns when a value is missing:

// Bail with fallback if None, continue with unwrapped value
use user <- Option.guard(maybeUser, <LoginPage />)
<ProfilePage user={user} />

See the Callback Flattening & Guards guide for the full pattern.