@ekz/option

Option/Maybe type to be used with flow.js

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@ekz/option
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Readme

Description

Simply get rid of all nulls in your code.

This is a clone of Scala's Option class to be used with flow.js.

Examples

// @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}`);
});

API

Table of Contents

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

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

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

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>

If you find any bugs or have a feature request, please open an issue on github!

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