对表达的类型感到困惑

Question

我有一个函数,我认为应该返回一个类型T.然而,它报告返回(T - > T),这对我来说肯定似乎是函数.这是代码:

let setContent content cell = { cell with Content = content }

let destroy = setContent Crater

let detonateMine cell = 
    function 
    | { Content = Mine } -> 
        destroy cell
    | { Content = Crater } -> 
        let errMessage = sprintf "The cell has already been denotated. (%i, %i)" cell.Location.X cell.Location.Y
        invalidOp errMessage
    | _ -> 
        let errMessage = 
            sprintf "The cell cannot be denotated. It does not contain a mine. (%i, %i)" cell.Location.X 
                cell.Location.Y
        invalidOp errMessage

setContent是T - > T.

毁灭是T - > T.

我有破坏测试,返回的值是T.

但是,引爆的类型是cell:T -> _arg1:T -> T._arg1来自哪里？

Answer 1

在这里,这个词function没有做你想要的.相反,它基本上创建了一个匿名函数.

一般来说

function | ...

相当于

fun y -> match y with | ...

(_arg1对应于y我添加的)

在你的情况下function改为:

match cell with

应该做你想做的事.