Js.Undefined
Provide utilities around undefined
Provides functionality for dealing with the 'a Js.undefined
type
let return: 'a => t('a);
Constructs a value of 'a Js.undefined
containing a value of 'a
let test: t('a) => bool;
Returns true
if the given value is empty
(undefined
), false
otherwise
let empty: t('a);
The empty value, undefined
let getUnsafe: t('a) => 'a;
let getExn: t('a) => 'a;
let bind: t('a) => Js.Fn.arity1(('a => 'b)) => t('b);
Maps the contained value using the given function
If 'a Js.undefined
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.undefined
let maybeGreetWorld (maybeGreeting: string Js.undefined) =
Js.Undefined.bind maybeGreeting (fun greeting -> greeting ^ " world!")
let iter: t('a) => Js.Fn.arity1(('a => unit)) => unit;
Iterates over the contained value with the given function
If 'a Js.undefined
contains a value, that value is unwrapped and applied to the given function.
let maybeSay (maybeMessage: string Js.undefined) =
Js.Undefined.iter maybeMessage (fun message -> Js.log message)
let fromOption: option('a) => t('a);
Maps 'a option
to 'a Js.undefined
Some a | -> | return a |
None | -> | empty |
let from_opt: option('a) => t('a);
let toOption: t('a) => option('a);
Maps 'a Js.undefined
to 'a option
return a | -> | Some a |
empty | -> | None |
let to_opt: t('a) => option('a);