相关疑难解决方法(0)

我想写点像

let timeit (x:'a->'b) =
    let start = System.DateTime.Now
    x
    let duration = System.DateTime.Now - start
    printfn "time usage = %A" duration.Milliseconds 
    ()

它适用于

let matrixtest() =
    let x = vector[1.;2.;4.]
    let y = matrix[[1.;2.;4.;];[3.;4.;9.;]]
    printfn "%A" (y * x)
    ()

但不是

let rec fib x = 
        match x with
        | 0 | 1 -> 1
        | n -> fib (n-1) + fib (n-2)

sa F#是静态类型的.

任何的想法？谢谢.