None()

The lack of a value.

Some(T)

A value of type T.

fn pub !=(other: ref Self) -> Bool {
  (self == other).false?
}

fn pub !=(other: ref Self) -> Bool
if
  T: Equal

Returns true if self and the given object are not equal to each other.

fn pub ==(other: ref Option[T]) -> Bool {
  match (self, other) {
    case (Some(a), Some(b)) -> a == b
    case (None, None) -> true
    case _ -> false
  }
}

fn pub ==(other: ref Option[T]) -> Bool
if
  T: Equal

Returns true if self and the given Option are equal.

Two options are considered equal to each other if:

1. They are both None

2. They are both some, and the wrapped values are equal to each other

Examples

Comparing two Some values:

Option.Some(10) == Option.Some(10) # => true
Option.Some(10) == Option.Some(20) # => false

Comparing a Some and a None:

Option.Some(10) == Option.None # => false

Comparing two None values:

Option.None == Option.None # => true

fn pub inline mut as_mut -> Option[mut T] {
  match self {
    case Some(v) -> Option.Some(v)
    case None -> Option.None
  }
}

fn pub inline mut as_mut -> Option[mut T: mut]
if
  T: mut

Returns an optional mutable reference to the wrapped value.

Examples

Option.Some([10]).as_mut # => Option.Some(mut [10])

fn pub inline as_ref -> Option[ref T] {
  match self {
    case Some(v) -> Option.Some(v)
    case None -> Option.None
  }
}

fn pub inline as_ref -> Option[ref T]

Returns an optional immutable reference to the wrapped value.

Examples

Option.Some(10).as_ref # => Option.Some(ref 10)
Option.None.as_ref     # => Option.None

fn pub inline clone -> Option[move T] {
  match self {
    case Some(v) -> Option.Some(v.clone)
    case None -> Option.None
  }
}

fn pub inline clone -> Option[move T]
if
  T: Clone

Creates a clone of self.

The returned value is an owned value that is the same type as the receiver of this method. For example, cloning a ref Array[Int] results in a Array[Int], not another ref Array[Int].

fn pub inline move else(block: fn -> Option[T]) -> Option[T] {
  if some? { self } else { block.call }
}

fn pub inline move else(block: fn -> Option[T]) -> Option[T]

Calls the supplied block if self is a None, returning the Option provided by the block argument.

If self is a Some, the Some itself is returned.

fn pub fmt(formatter: mut Formatter) {
  match self {
    case Some(v) -> formatter.tuple('Some').field(v).finish
    case None -> formatter.tuple('None').finish
  }
}

fn pub fmt(formatter: mut Formatter)
if
  T: Format

Formats self in a human-readable format for debugging purposes.

fn pub move get -> T {
  or_panic_with('Option.get expects a Some(_), but a None is found')
}

fn pub move get -> T

Returns the value wrapped by Some, or panics if self is a None.

Examples

Option.Some(10).get # => 10

fn pub inline move map[R](block: fn (T) -> R) -> Option[R] {
  match self {
    case Some(v) -> Option.Some(block.call(v))
    case None -> Option.None
  }
}

fn pub inline move map[R](block: fn (T) -> R) -> Option[R]

Maps an Option[T] to an Option[R] by wrapping the value returned by the provided closure.

The closure is to return a value to be wrapped in a Some. If used on a None, None itself is returned.

Examples

Mapping an Option to a new Option:

Option.Some(10).map fn (num) { num * 2 } # => Option.Some(20)

Mapping a None:

Option.None.map fn (x) { x * 2 } # => Option.None

fn pub inline none? -> Bool {
  match self {
    case Some(_) -> false
    case None -> true
  }
}

fn pub inline none? -> Bool

Returns true for a None, false otherwise.

Examples

Option.Some(10).none? # => false
Option.None.none?     # => true

fn pub inline move ok_or[E](error: E) -> Result[T, E] {
  match self {
    case Some(v) -> Result.Ok(v)
    case _ -> Result.Error(error)
  }
}

fn pub inline move ok_or[E](error: E) -> Result[T, E]

Transforms self into a Result[T, E], mapping an Option.Some(T) to Result.Ok(T) and a Option.None to Result.Error(E).

The argument is eagerly evaluated. If this isn't desired, use Option.ok_or_else instead.

Examples

Option.Some(10).ok_or('oops!') # => Result.Ok(10)
Option.None.ok_or('oops!')     # => Result.Error('oops!')

fn pub inline move ok_or_else[E](error: fn -> E) -> Result[T, E] {
  match self {
    case Some(v) -> Result.Ok(v)
    case _ -> Result.Error(error.call)
  }
}

fn pub inline move ok_or_else[E](error: fn -> E) -> Result[T, E]

Transforms self into a Result[T, E], mapping an Option.Some(T) to Result.Ok(T) and a Option.None to Result.Error(E) where E is the return value of the given closure.

Examples

Option.Some(10).ok_or_else(fn { 'oops!' }) # => Result.Ok(10)
Option.None.ok_or_else(fn { 'oops!' })     # => Result.Error('oops!')

fn pub inline move or(default: T) -> T {
  match self {
    case Some(v) -> v
    case None -> default
  }
}

fn pub inline move or(default: T) -> T

Returns the value wrapped by Some, or returns default if self is a None.

Examples

Option.Some(10).or(0) # => 10
Option.None.or(0)     # => 0

fn pub inline move or_else(block: fn -> T) -> T {
  match self {
    case Some(v) -> v
    case None -> block.call
  }
}

fn pub inline move or_else(block: fn -> T) -> T

Returns the value wrapped by Some, or returns the closure's return value if self is a None.

Examples

Option.Some(10).or_else fn { 0 } # => 10
Option.None.or_else fn { 0 }     # => 0

fn pub inline move or_panic_with(message: String) -> T {
  match self {
    case Some(v) -> v
    case _ -> panic(message)
  }
}

fn pub inline move or_panic_with(message: String) -> T

Returns the value wrapped by Some, or panics with the given message if self is a None.

Examples

Option.Some(10).or_panic_with('a number must be present') # => 10

fn pub inline some? -> Bool {
  match self {
    case Some(_) -> true
    case None -> false
  }
}

fn pub inline some? -> Bool

Returns true for a Some, false otherwise.

Examples

Option.Some(10).some? # => true
Option.None.some?     # => false

fn pub inline move then[R](block: fn (T) -> Option[R]) -> Option[R] {
  match self {
    case Some(v) -> block.call(v)
    case None -> Option.None
  }
}

fn pub inline move then[R](block: fn (T) -> Option[R]) -> Option[R]

Maps an Option[T] to an Option[R] using the Option returned by the provided closure.

The closure is to return a new Option. If used on a None, None itself is returned.

This process is sometimes referred to as a "flat map". Inko uses the name "then" because this reads more nicely when chaining multiple instances of this method together.

fn pub move zip[O](other: Option[O]) -> Option[(T, O)] {
  match self {
    case Some(ours) -> {
      match other {
        case Some(theirs) -> Option.Some((ours, theirs))
        case _ -> Option.None
      }
    }
    case _ -> Option.None
  }
}

fn pub move zip[O](other: Option[O]) -> Option[(T, O)]

Zips self with another Option.

If both Option values are a Some, this method returns a Some containing a tuple of both values. If either is a None, None is returned.