@ekz/option

Simply get rid of all nulls in your code.
This is a clone of Scala's Option class to be used with flow.js.

// @flow

let valueA = Option.of(null).map(x => x + 2).getOrElse(() => 0);
// valueA = 0

let valueB = Some('any object').flatMap(x => Some(`${x}!!!`)).getOrUndefined();
// valueB = 'any object!!!'

let valueC = Some(null).flatMap(() => Option.of(2)).map(x => x * 3).getOrElse(() => 0);
// valueC = 6

let valueD = Some(1).mapNullable(() => null).getOrReturn(-1);
// valueD = -1

Some(1).equals(Some(1))
// true

None.equals(None)
// true

Some('abc').equals(None)
// false

None.isDefined; // false
Some(1).isDefined; // true
Some(1).isEmpty; // false
Some(null).isEmpty; // false! Option<null> is valid!

Some('foo').get(); // 'foo'
None.get(); // throws an error, use getOrElse or getOrUndefined instead

Some(3).filter(x => x % 2 === 0); // None

Some('bar').forEach(x => {
    console.log(`my value: ${x}`);
});

Table of Contents

• Option

-   [get](#get)
-   [isEmpty](#isempty)
-   [isDefined](#isdefined)
-   [map](#map)
-   [mapNullable](#mapnullable)
-   [flatMap](#flatmap)
-   [forEach](#foreach)
-   [filter](#filter)
-   [getOrElse](#getorelse)
-   [getOrReturn](#getorreturn)
-   [getOrUndefined](#getorundefined)
-   [equals](#equals)
-   [toJSON](#tojson)
-   [of](#of)
-   [None](#none)
-   [Some](#some)

• None
• Some

Option

Represents optional values. Instances of Option are either an instance of Some or the object None.
Parameters

• $privateToken any

get

Returns the option's value.
Type: function (): A

isEmpty

Returns true if the option is None, false otherwise.
Type: boolean

isDefined

Returns true if the option is an instance of Some, false otherwise.
Returns boolean

map

Returns a Some containing the result of applying f to this Option's value if this Option is nonempty.
Parameters

• f function (A): B

Returns Option<B>

mapNullable

Like map, but if resulting value is null, then returns None.
Parameters

• f function (A): B?

Returns Option<B>

flatMap

Returns the result of applying f to this Option's value if this Option is nonempty. Returns None if this Option is empty. Slightly different from map in that f is expected to return an Option (which could be None).
Parameters

• f function (A): Option<B>

Returns Option<B>

forEach

Apply the given procedure f to the option's value, if it is nonempty.
Parameters

• f function (A): any

Returns void

filter

Returns this Option if it is nonempty and applying the predicate to this Option's value returns true.
Parameters

• predicate function (A): boolean

Returns Option<A>

getOrElse

Returns the option's value if the option is nonempty, otherwise return the result of evaluating other.
Parameters

• other function (): B

Returns (A | B)

getOrReturn

Returns the option's value if the option is nonempty, otherwise return other.
Parameters

• other B

Returns (A | B)

getOrUndefined

Returns the option's value if the option is nonempty, otherwise returns undefined.
Returns (A | void)

equals

Compares the option's value with other option's value and returns true when they match. None always matches other None.
Parameters

• other Option<B>

Returns boolean

toJSON

Returns value if present, null otherwise. If value contains a method toJSON, returns the result of method call.
Returns any

of

An Option factory which creates Some(x) if the argument is not null, and None if it is null.
Parameters

• value V?

Returns Option<V>

None

The empty None object
Type: Option<any>

Some

Creates Some(x). Note that Some(null) is valid.
Type: function (value: A): Option<A>

None

The empty None object.
Type: Option<any>

Some

Creates Some(x). Note that Some(null) is valid.
Parameters

• value A

Returns Option<A>