Handling Optional/Nullable Fields and Default Values in Schema Parsing

const ValueSchema = Schema.literal("A");
type Value = Schema.Schema.To<typeof ValueSchema>;

const ValueArraySchema: Schema.Schema<string, Value[]> = pipe(
    Schema.string,
    Schema.split(","),
    Schema.compose(Schema.array(ValueSchema)),
);

const ValueArraySchema: Schema.Schema<string | null, Value[]> = pipe(
    Schema.optionFromNullable(Schema.string),
    
    // How do I:
    // - handle Some<string> to do the same transformations as above
    // - handle None to return a default value (in this case [] as Value[])
);