F# Fable-无法获取泛型参数的类型信息，请内联或插入类型解析器

我试图在fable中编写一个通用的json解码函数。它似乎是在FSharp中编译的，但我得到了以下代码的错误消息：

[使用Thoth.Json库和Fable.PowerPack中的Fetch库]

let autoDecoder<'a> (json:string) (value:obj) : Result<'a, Thoth.Json.Decode.DecoderError> =
    let tryDecode = Thoth.Json.Decode.Auto.fromString<'a>(json)
    let getDecoderError (str:string) : Thoth.Json.Decode.DecoderError = ( "Auto decode Error", Thoth.Json.Decode.FailMessage str) 
    Result.mapError getDecoderError tryDecode

let自动解码器=
让tryDecode=Thoth.Json.Decode.Auto.fromString函数保持通用性

感谢
我是fable的新手，但我无法让它工作，fable编译器不允许在没有指定类型的情况下自动解码-此处失败：

Thoth.Json.Decode.Auto.fromString<'a>(str, true)

Thoth.Json.Decode.Auto.fromString
模型，Cmd.ofPromise getCustomers（）LoadedCustomerData获取错误
|已加载的客户数据响应->
匹配
|Ok qdj->{model with gridData=queryDataFromJson qdj；message=“Loaded Customer Data”}，Cmd.none
|错误str->{model with message=str}，Cmd.none
我想寓言是在告诉你要像这样使用
内联
：

let inline autoDecoder<'a> (json:string) (value:obj) : Result<'a, Thoth.Json.Decode.DecoderError> =
    let tryDecode = Thoth.Json.Decode.Auto.fromString<'a>(json)
    let getDecoderError (str:string) : Thoth.Json.Decode.DecoderError = ( "Auto decode Error", Thoth.Json.Decode.FailMessage str) 
    Result.mapError getDecoderError tryDecode

谢谢，这是我为寓言而编撰的东西；但函数本身不起作用——json是一个空字符串，我只是使用了另一个“答案”，因为我没有时间去弄清楚原因
type Msg =
    | Start
    | LoadedCustomerData of Result<QueryDataForJson, string>
..

let getCustomers () = promise {
    let! response = Fetch.fetch "http://localhost:5000/spa/api/customers" http.getHeaders
    let! text = response.text()
    return Thoth.Json.Decode.Auto.fromString<QueryDataForJson>(text, true)
}
..
let update (msg:Msg) (model:Model) =
    match msg with
    | Start ->
        model, Cmd.ofPromise getCustomers () LoadedCustomerData FetchError
    | LoadedCustomerData resp ->
        match resp with
            | Ok qdj -> { model with gridData= queryDataFromJson qdj; message= "Loaded Customer Data"  }, Cmd.none
            | Error str -> { model with message = str }, Cmd.none

let inline autoDecoder<'a> (json:string) (value:obj) : Result<'a, Thoth.Json.Decode.DecoderError> =
    let tryDecode = Thoth.Json.Decode.Auto.fromString<'a>(json)
    let getDecoderError (str:string) : Thoth.Json.Decode.DecoderError = ( "Auto decode Error", Thoth.Json.Decode.FailMessage str) 
    Result.mapError getDecoderError tryDecode

let inline autoDecoder<'a> (json:string) : Result<'a, Thoth.Json.Decode.DecoderError> =
    Thoth.Json.Decode.Auto.fromString<'a> json
    |> Result.mapError (fun (str:string) ->  "Auto decode Error", Thoth.Json.Decode.FailMessage str)