Docs / API / Js / Nullable

Nullable

Contains functionality for dealing with values that can be both null and undefined

t

Deprecated

RESCRIPT

@unboxed
type t<'a> = nullable<'a> =
  | Value('a)
  | @as(null) Null
  | @as(undefined) Undefined

return

Deprecated

RESCRIPT

let return: 'a => t<'a>

Constructs a value of Js.null_undefined<'a> containing a value of 'a.

isNullable

Deprecated

RESCRIPT

let isNullable: t<'a> => bool

Returns true if the given value is null or undefined, false otherwise.

null

Deprecated

RESCRIPT

let null: t<'a>

The null value of type Js.null_undefined<'a>.

undefined

Deprecated

RESCRIPT

let undefined: t<'a>

The undefined value of type Js.null_undefined<'a>.

bind

Deprecated

RESCRIPT

let bind: (t<'a>, 'a => 'b) => t<'b>

Maps the contained value using the given function.

If Js.null_undefined<'a> contains a value, that value is unwrapped, mapped to a 'b using the given function a' => 'b, then wrapped back up and returned as Js.null_undefined<'b>.

Examples

RESCRIPT
let maybeGreetWorld = (maybeGreeting: Js.null_undefined<string>) =>
  Js.Null_undefined.bind(maybeGreeting, greeting => greeting ++ " world!")

iter

Deprecated

RESCRIPT

let iter: (t<'a>, 'a => unit) => unit

Iterates over the contained value with the given function. If Js.null_undefined<'a> contains a value, that value is unwrapped and applied to the given function.

Examples

RESCRIPT
let maybeSay = (maybeMessage: Js.null_undefined<string>) =>
  Js.Null_undefined.iter(maybeMessage, message => Js.log(message))

fromOption

Deprecated

RESCRIPT

let fromOption: option<'a> => t<'a>

Maps option<'a> to Js.null_undefined<'a>. Some(a) => a None => undefined

from_opt

Deprecated

RESCRIPT

let from_opt: option<'a> => t<'a>

toOption

Deprecated

RESCRIPT

let toOption: t<'a> => option<'a>

Maps Js.null_undefined<'a> to option<'a>. a => Some(a) undefined => None null => None

to_opt

Deprecated

RESCRIPT

let to_opt: t<'a> => option<'a>