f# - 此表达式应具有类型 'obj' 但此处具有类型 'string'

Question

下面的代码有一个类型错误，比如“这个表达式应该有‘obj’类型，但这里有‘string’类型”

    let fiveDaysForecast (model: CityForecast) = 
        let fiveDays = model.Days |> List.truncate 5
        let city = if model.Country |> String.IsNullOrWhiteSpace then model.City else sprintf "%s, %s" model.City model.Country 
        View.StackLayout(padding = 20.0, verticalOptions = LayoutOptions.FillAndExpand,
            children = [ 
                View.Label(text=city.ToUpper(), textColor=Color.Beige, backgroundColor=Color.FromHex("#0F4D8FAC"), fontSize=40, fontAttributes=FontAttributes.Bold, horizontalTextAlignment=TextAlignment.Center)
                empty 20.
                View.Grid(
                    rowdefs=["*"],
                    coldefs=[ for _ in fiveDays -> "*" ],
                    children = (fiveDays |> List.mapi (day 0) ) )
                ])

这行代码的错误 coldefs=[ for _ in fiveDays -> "*"], 由于 "*"

我该如何解决？

Answer 1

根据 Fabulous Guide ( https://fsprojects.github.io/Fabulous/views-perf.html )，您需要将列表元素装箱:

coldefs=[ for _ in fiveDays -> box "*" ]