Function oneOf

Combine multiple decoders where any of them can match for the resulting decoder to succeed.

Example

For this example we assume that we have an API endpoint that returns either a numeric string or a number. Something like this:

[
    { id: 1 },
    { id: '2' },
]
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which can be decoded to a flat numeric array like this:

const string_to_number_decoder = Decode.andThen(str => {
    const v = parseInt(str, 10);

    if (typeof v === 'number' && !isNaN(v)) {
        return Decode.succeed(v);
    } else {
        return Decode.fail(expected('a number string', str));
    }
}, Decode.string);

const decoder = Decode.oneOf([
    Decode.number,
    string_to_number_decoder,
]);

// This gives us an array like [1, 2], where both values are actual
// numbers
decode(Decode.many(Decode.field('id', decoder)), [
    { id: 1 },
    { id: '2' },
]);
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