为什么“-1”不能减1？

Question

我试图与PDC2008 Intro to F# video一起编码。我在下面显示的代码片段的最后一行中收到错误（演示者没有得到）“错误1此值不是函数，无法应用”。我在Visual Studio 2008 shell上运行Fsharp-1.9.6.2。最后一行中的startPrice符号带有下划线红色，鼠标悬停时出现相同的错误。提前谢谢！

type StockAnalyzer (lprices, days) = 
    let prices =
        lprices
        |> Seq.map snd
        |> Seq.take days
    static member GetAnalyzers (tickers,days) = 
        tickers
        |> Seq.map loadPrices
        |> Seq.map (fun prices -> new  StockAnalyzer (prices, days))
    member s.Return = 
        let  lastPrice = prices |> Seq.nth 0
        let  startPrice = prices |> Seq.nth (days - 1)
        lastPrice / startPrice  -1.

Answer 1

尝试在“ - ”和“1”之间加一个空格。 F＃编译器将-1解释为字面上的负值1而不是减1。