Variable Decoder

Decoder: { _tag: "Decoder" } & {
    array: <A>(inner: Decoder<A>) => Decoder<A[]>;
    boolean: Decoder<boolean>;
    either: {
        discriminated: <L, R>(
            config: { leftTag: string; rightTag: string; tag: string },
            left: Decoder<L>,
            right: Decoder<R>,
        ) => Decoder<Either<L, R>>;
        envelope: <L, R>(
            shape: { err: Decoder<L>; ok: Decoder<R> },
        ) => Decoder<Either<L, R>>;
    };
    list: <A>(inner: Decoder<A>) => Decoder<List<A>>;
    map: <V>(inner: Decoder<V>) => Decoder<Map<string, V>>;
    nullable: <A>(inner: Decoder<A>) => Decoder<A | null>;
    number: Decoder<number>;
    object: <T extends Record<string, unknown>>(
        shape: { [K in string | number | symbol]: Decoder<T[K]> },
    ) => Decoder<T>;
    option: <A>(inner: Decoder<A>) => Decoder<Option<A>>;
    string: Decoder<string>;
    tagged: {
        either: <L, R>(
            left: Decoder<L>,
            right: Decoder<R>,
        ) => Decoder<Either<L, R>>;
        list: <A>(inner: Decoder<A>) => Decoder<List<A>>;
        map: <V>(inner: Decoder<V>) => Decoder<Map<string, V>>;
        obj: <T extends Record<string, unknown>>(
            shape: { [K in string | number | symbol]: Decoder<T[K]> },
        ) => Decoder<T>;
        option: <A>(inner: Decoder<A>) => Decoder<Option<A>>;
        try: <A>(inner: Decoder<A>) => Decoder<Try<A>>;
    };
    unknown: Decoder<unknown>;
}

Decoder namespace: combinators for converting unknown into typed values.

Decoder.string / .number / .boolean / .unknown / .nullable(inner) — leaf primitives
Decoder.option(inner) — null-bias Option (null → None, else inner → Some)
Decoder.either.envelope({ok, err}) / .discriminated({...}, l, r) — Either variants
Decoder.list(inner) / .array(inner) / .map(inner) / .object(shape) — composites; accumulate child failures
Decoder.tagged.option/either/try/list/map/obj(inner?) — round-trip the {_tag, value} shape used by functype's built-in .toJSON() (for functype-to-functype services)

Variable Decoder

Settings