Module Js_null

Provides functionality for dealing with the 'a Js.null type

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 test : 'a t -> bool

Returns true if the given value is empty (null), false otherwise

  • deprecated Use = Js.null directly
val empty : 'a t

The empty value, null

val getUnsafe : 'a t -> 'a
val getExn : 'a t -> 'a
val bind : 'a t -> ('a -> 'b) Js.Fn.arity1 -> '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 (fun greeting -> greeting ^ " world!")
val iter : 'a t -> ('a -> unit) Js.Fn.arity1 -> 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 (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 from_opt : 'a option -> 'a t
  • deprecated Use fromOption instead
val toOption : 'a t -> 'a option

Maps 'a Js.null to 'a option

return a -> Some a
empty -> None
val to_opt : 'a t -> 'a option
  • deprecated Use toOption instead