Support for tuples. about ts.data.json HOT 5 CLOSED

type StringPair = readonly [string,string]
type ConfigInfo = readonly StringPair[]

function isArray(value: any): value is any[] {
    return Array.isArray(value)
}

function jsonDecoderErrorMessagePrimitive(value: any, tag: string): string {
    return `${JSON.stringify(value)} is not a valid ${tag}`
}

const stringPairDecoder: JsonDecoder.Decoder<StringPair> = new JsonDecoder.Decoder(value => {
    if(isArray(value)){
        if(value.length===2) {
            const fst = JsonDecoder.string.decode(value[0])
            if(fst.isOk()){
                const snd = JsonDecoder.string.decode(value[1])
                if(snd.isOk()){
                    return ok<StringPair>([fst.value,snd.value])
                }
            }
        }
    }
    return err<StringPair>(jsonDecoderErrorMessagePrimitive(value, "StringPair"))
})

const configInfoDecoder: JsonDecoder.Decoder<ConfigInfo> =
    JsonDecoder.array(stringPairDecoder, "ConfigInfo")