result-js

import * as mod from "https://deno.land/x/result_js/mod.ts";

import {
  Err,
  Ok,
  type Result,
  unwrap,
} from "https://deno.land/x/result_js/mod.ts";
import { assertThrows } from "https://deno.land/std/testing/asserts.ts";

function divide(
  numerator: number,
  denominator: number,
): Result<number, string> {
  if (!denominator) return Err("divide by 0");

  return Ok(numerator / denominator);
}

const opt = divide(100, 0);
assertThrows(() => unwrap(opt));