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Module

x/fun/mod.ts>refinement.undefinable

A collection of algebraic data types, lenses, and schemables based on a light weight higher kinded type implementation. Written for deno.
baetheus/fun
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function refinement.undefinable
import { refinement } from "https://deno.land/x/fun@v2.0.0/mod.ts";
const { undefinable } = refinement;

Turn a Refinement<A, B> into Refinement<undefined | A, undefined | B>.

Examples

Example 1

import * as R from "./refinement.ts";

const test = R.undefinable(R.number);

const result1 = test(null); // false
const result2 = test(1); // true, variable is now undefined | number
const result3 = test("hello"); // false
const result4 = test(undefined); // true, variable is now undefined | number

Type Parameters

A
B extends A

Returns

Refinement<A | undefined, B | undefined>