type alias None

import { type None } from "https://deno.land/x/eitherway@0.10.0/lib/core/mod.ts";

None

None represents the absence of a value and is the opinionated, composable equivalent of undefined.

It support coercion to the falsy representation of primitive types Furthermore, it implements the iterator protocol and returns undefined when it gets JSON encoded via JSON.stringify()

Please checkout Some for the opposite case.

Examples

Example 1

import { assert } from "./assert.ts";
import { Option, None, Some } from "./option.ts";

const none = None;
const rec = { a: 1, b: none };
const arr = [ ...none ];

const encode = JSON.stringify;

//TS Bug: https://github.com/microsoft/TypeScript/issues/39064
assert(none instanceof (None as any) === true);
assert(none.isNone() === true);
assert(none.isSome() === false);
assert(none.unwrap() === undefined);
assert(String(none) === "");
assert(Number(none) === 0);
assert(none[Symbol.toPrimitive]() === false);
assert(Boolean(none) === true); //object always evaluate to true
assert(encode(rec) === encode({ a: 1 }));
assert(arr.length === 0);

definition: _None

variable None

import { None } from "https://deno.land/x/eitherway@0.10.0/lib/core/mod.ts";