Null (melange.Js.Null)

type +'a t = 'a Js.null

Local alias for 'a Js.null

val return : 'a -> 'a t

Constructs a value of 'a Js.null containing a value of 'a

val empty : 'a t

The empty value, null

val getUnsafe : 'a t -> 'a

val getExn : 'a t -> 'a

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

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

Maps the contained value using the given function

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

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

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

Iterates over the contained value with the given function

If 'a Js.null contains a value, that value is unwrapped and applied to the given function.

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

val fromOption : 'a option -> 'a t

Maps 'a option to 'a Js.null

Some a	->	return a
None	->	empty

val toOption : 'a t -> 'a option

Maps 'a Js.null to 'a option

return a	->	Some a
empty	->	None