Module Js.Nullable

Utility functions on nullable

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

type +'a t = 'a Js.nullable

type t(+'a) = Js.nullable('a);

Local alias for 'a Js.nullableJs.nullable('a)

val return : 'a -> 'a t

let return: 'a => t('a);

Constructs a value of 'a Js.nullableJs.nullable('a) containing a value of 'a

val isNullable : 'a t -> bool

let isNullable: t('a) => bool;

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

val null : 'a t

let null: t('a);

The null value of type 'a Js.nullableJs.nullable('a)

val undefined : 'a t

let undefined: t('a);

The undefined value of type 'a Js.nullableJs.nullable('a)

val map : f:('a -> 'b) Js.Fn.arity1 -> 'a t -> 'b t

let map: f:Js.Fn.arity1(('a => 'b)) => t('a) => t('b);

val bind : f:('a -> 'b t) Js.Fn.arity1 -> 'a t -> 'b t

let bind: f:Js.Fn.arity1(('a => t('b))) => t('a) => t('b);

Binds the contained value using the given function

If 'a Js.nullableJs.nullable('a) contains a value, that value is unwrapped, mapped to a 'b using the given function a' -> 'ba' => 'b, then wrapped back up and returned as 'b Js.nullableJs.nullable('b)

let maybeGreetWorld (maybeGreeting: string Js.nullable) =
  Js.Nullable.bind maybeGreeting ~f:(fun greeting -> greeting ^ " world!")

let maybeGreetWorld = (maybeGreeting: Js.nullable(string)) =>
  Js.Nullable.bind(maybeGreeting, ~f=greeting => greeting ++ " world!");

val iter : f:('a -> unit) Js.Fn.arity1 -> 'a t -> unit

let iter: f:Js.Fn.arity1(('a => unit)) => t('a) => unit;

Iterates over the contained value with the given function

If 'a Js.nullableJs.nullable('a) contains a value, that value is unwrapped and applied to the given function.

let maybeSay (maybeMessage: string Js.nullable) =
  Js.Nullable.iter maybeMessage ~f:(fun message -> Js.log message)

let maybeSay = (maybeMessage: Js.nullable(string)) =>
  Js.Nullable.iter(maybeMessage, ~f=message => Js.log(message));

val fromOption : 'a option -> 'a t

let fromOption: option('a) => t('a);

Maps 'a optionoption('a) to 'a Js.nullableJs.nullable('a)

Some a	return a
None	undefined

val toOption : 'a t -> 'a option

let toOption: t('a) => option('a);

Maps 'a Js.nullableJs.nullable('a) to 'a optionoption('a)

return a	Some a
undefined	None
null	None