Go-style functional type-safe error handling

error.ts

const checkNumber = check((thing: unknown) => {
    if (typeof thing === 'number') {
        return thing;
    }

    return ko(new E.NOT_NUMBER(thing));
});

const main = check(() => {
    const [number0, e0] = checkNumber(9);
    if (caught(number0)) return ko(e0);

    const [number1, e1] = checkNumber('9');
    if (caught(number1)) return ko(e1);
});

const E = {
    NOT_NUMBER: error((v: unknown) => {
        return `not a valid number ${JSON.stringify(v)}`;
    }),
};