option.ts

export type Option<T> = {
    unwrap: (message?: string) => T
    match: <R>(matchers: OptionMatchers<T, R>) => R
}

type OptionMatchers<T, R> = {
    onSome: (value: T) => R
    onNone: () => R
}

type OptionValue<T> =
    | Some<T>
    | None

type Some<T> = {
    __isSome: true
    value: T
}

type None = {
    __isSome: false
}

const some = <T>(value: T) => toOption({
    __isSome: true,
    value,
})

const none = () => toOption({
    __isSome: false,
})

const toOption = <T>(option: OptionValue<T>): Option<T> => {

    const unwrap = (message?: string): T => {

        if (!message) {
            console.log('Either provide a failure message to <option>.unwrap or use <option>.match');
        }

        if (option.__isSome) {
            return option.value;
        }

        throw new Error(message ?? 'Option was not Some');
    }

    const match = <R>(matchers: OptionMatchers<T, R>): R =>
        option.__isSome
            ? matchers.onSome(option.value)
            : matchers.onNone();

    return ({
        unwrap,
        match,
    })
}

export const object = Object.freeze({
    some,
    none,
});