Adding Built-in Refinements to `Data.case`

export interface First extends D.Case {
    _tag: "First";
    readonly first: number;
};

export const First = D.case<First>();

export interface Second extends D.Case {
    _tag: "Second";
    readonly second: string;
};

export const Second = D.case<Second>();

export type Thing = First | Second;

// TODO can Data.Case give this for free?
export const isFirst: P.Refinement<Thing, First> =
    (thing): thing is First =>
        pipe(
            M.value(thing),
            M.tag('First', constTrue),
            M.tag('Second', constFalse),
            M.exhaustive,
        );

export const isFirst = D.isCase<First>();