// The following code demonstrates the use of reference // cells to enable partially applied arguments to be changed // by later code. let increment1 delta number = number + delta let mutable myMutableIncrement = 10 // Closures created by partial application and literals. let incrementBy1 = increment1 1 let incrementBy2 = increment1 2 // Partial application of one argument from a mutable variable. let incrementMutable = increment1 myMutableIncrement myMutableIncrement <- 12 // This line prints 110. printfn "%d" (incrementMutable 100) let myRefIncrement = ref 10 // Partial application of one argument, dereferenced // from a reference cell. let incrementRef = increment1 !myRefIncrement myRefIncrement := 12 // This line also prints 110. printfn "%d" (incrementRef 100) // Reset the value of the reference cell. myRefIncrement := 10 // New increment function takes a reference cell. let increment2 delta number = number + !delta // Partial application of one argument, passing a reference cell // without dereferencing first. let incrementRef2 = increment2 myRefIncrement myRefIncrement := 12 // This line prints 112. printfn "%d" (incrementRef2 100)-----------------
let mutable x =1
let x' =x
x<-2
x' (还是1,它拷贝了x的副本，因此不会被x的改变而改变s)